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Objective The measurement of C-peptide immunoreactivity (CPR) is essential for evaluating the pancreatic β-cell function and selecting appropriate therapeutic agents in patients with diabetes mellitus. The meal tolerance test (MTT) is simple to administer physiological insulin-stimulating test. Previous studies have reported that several CPR-related indices are useful markers for predicting insulin requirement in type 2 diabetes. In the present study, we investigated the serum CPR response during the MTT in hospitalized patients with type 2 diabetes mellitus in order to clarify the clinical utility of the MTT. Methods We performed the MTT using a test meal with timed measurements of the serum CPR level based on the oral glucose tolerance test over 180 minutes and tested the correlation of various CPR-related indices and clinical factors in patients with type 2 diabetes mellitus. Patients The subjects were patients with type 2 diabetes mellitus who had been admitted to our hospital for diabetes management and education. The final study population consisted of 68 patients. Results The fasting CPR level was correlated with the 24-hour urinary CPR excretion and body mass index. The serum CPR level at 120 minutes in the MTT was strongly correlated with the area under the curve of CPR during the MTT. The patients who needed insulin therapy at 6 months after hospitalization showed a significant lower incremental CPR value from 0 to 120 minutes in the MTT than those who did not need insulin therapy. Conclusion The plasma C-peptide levels at 0 and 120 minutes in the MTT provide essential information for the clinical management of patients with type 2 diabetes mellitus.

Aims/Introduction The prevalence of clinical polyneuropathies (ClinPNs) or nerve conduction abnormality (NCA) in the groups stratified by glucose tolerance, individual components of metabolic syndrome (metabolic syndrome [MetS] components: hypertension, dyslipidemia, obesity) and MetS defined by the International Diabetes Federation consensus was investigated in the Japanese general population. Factors associated with ClinPN and NCA were also identified. Materials and Methods A total of 625 examinees of regional medical checkup programs were recruited to this cross‐sectional study. ClinPNs were diagnosed by the Toronto Consensus. NCA was judged by at least one bilateral abnormality of sural nerve action potential amplitude or conduction velocity measured by a point‐of‐care nerve conduction device (DPNCheck). Clinical factors associated with ClinPNs or NCA were examined by multiple logistic regression analysis. Deteriorating factors of sural nerve action potential amplitude or conduction velocity values were also investigated in participants without diabetes (n = 550). Results As for glucose tolerance, ClinPNs or NCA significantly increased only in known diabetes patients compared with other groups. There was no difference between prediabetes and the normal group. The prevalence of ClinPNs and NCA was not significantly related to MetS or MetS’ components, except for frequent NCA in obesity. The factors significantly associated with both NCA and ClinPNs were smoking and known diabetes. In non‐diabetic participants, aging, tall height and hypertension were significant deteriorating factors of nerve conduction functions. Conclusions In Japan, ClinPNs and NCA were increased in known diabetes patients, but did not increase in participants with prediabetes, MetS and MetS’ components. Smoking and known diabetes were factors significantly associated with ClinPNs or NCA. Hypertension might be a modifiable deteriorating factor of nerve function.

T2DM is a common disease progressed over the long duration of life. Because of lacking apparent symptoms and signs in many cases, interrelationship between patient and doctor becomes complicated...

Aims/Introduction As the extensor digitorum brevis muscle is a small muscle in the most distal part of the legs, its atrophy (EDBA) might reflect symmetric polyneuropathy (SPN). We aimed to clarify the EDBA‐related factors and the usefulness of bilateral EDBA detection for diagnosing SPN, especially diabetic SPN (DSPN). Materials and Methods In 1,893 participants from the Japanese general population (investigation I) and 133 established diabetes patients (investigation II), relationships between EDBA and various factors including the traditional sitting style called “seiza’” (kneeling and sitting on one’s heels) were investigated. Analyses were carried out by univariate and multivariate analysis, and SPN or DSPN was diagnosed by the criteria of “Probable DSPN” of the Toronto Consensus. The validity of EDBA detection for diagnosing SPN/DSPN was also evaluated. Results Investigation I: EDBA was more prevalent in women than men (44% vs 20%). Significant EDBA‐related factors were aging and seiza habit regardless of sex. Male‐specific EDBA‐related factors were SPN and known diabetes. In men without seiza habit, EDBA was significantly associated with SPN regardless of diabetes, so EDBA seemed to be a useful sign for diagnosing SPN/DSPN. Investigation II: In men, DSPN was more prevalent in the EDBA group than the non‐EDBA group (71% vs 33%). Sensitivity, specificity, positive predictive value and kappa coefficient of EDBA detection for diagnosing DSPN were 44, 87, 67% and 0.323, showing fair agreement. Conclusions EDBA detection might be a useful method to screen for distal symmetric polyneuropathy, such as DSPN in men, although the exclusion of individuals with seiza habit is necessary to improve accuracy., Extensor digitorum brevis atrophy detection might be a useful method to screen for distal symmetric polyneuropathy, such as diabetic symmetric polyneuropathy in men, although the exclusion of individuals with seiza habit is necessary to improve accuracy.

Aims/Introduction To explore the relationships between periodontitis and microvascular complications as well as glycemic control in type 2 diabetes patients. Materials and Methods This multicenter, hospital-based, cross-sectional study included 620 patients with type 2 diabetes. We compared the prevalence and severity of periodontitis between patients with ≥1 microvascular complication and those without microvascular complications. We also compared the prevalence and severity of periodontitis among patients with different degrees of glycemic control. Results After adjusting for confounding factors, multiple logistic regression analysis showed that the severity of periodontitis was significantly associated with the number of microvascular complications (odds ratio 1.3, 95% confidence interval 1.1–1.6), glycated hemoglobin ≥8.0% (64 mmol/mol; odds ratio 1.6; 95% confidence interval 1.1–2.3), and older age (≥50 years; odds ratio 1.7; 95% confidence interval 1.1–2.6). However, the prevalence of periodontitis was not significantly associated with the number of microvascular complications, but was associated with male sex, high glycated hemoglobin (≥8.0% [64 mmol/mol]), older age (≥40 years), longer duration of diabetes (≥15 years) and fewer teeth (≤25). Furthermore, propensity score matching for age, sex, diabetes duration and glycated hemoglobin showed that the incidence of severe periodontitis was significantly higher among patients with microvascular complications than among those without microvascular complications (P < 0.05). Conclusions The number of microvascular complications is a risk factor for more severe periodontitis in patients with type 2 diabetes, whereas poor glycemic control is a risk factor for increased prevalence and severity of periodontitis.

We measured pain threshold of intra-epidermal nerve terminal (PINT) which is a simple and noninvasive method that can measure pain threshold of A delta fiber by intra-epidermal electrical stimulation. We aimed to investigate normal value, prevalence of abnormality and clinically associated factors to PINT and quantitative vibratory perception threshold (QVT). PINT and QVT were measured by a portable peripheral nerve testing device PNS-7000, and a vibration sensation meter AU 02-B in 656 Japanese regional health checkup examinees (40-75 years old; years old). Glucose tolerance; normal (N), pre-DM, newly diagnosed DM (NDM) and known DM (KDM), and neuropathic findings (pain, paresthesia, numbness in legs and reduced ATRs) were also determined. Relationship between age, glucose tolerance, neuropathic findings and PINT or QVT were investigated by simple and multivariate analyses. In 445 non-DM subjects without neuropathic findings, normal limit value of PINT (mA) was set by quantile regression method, and relationship between prevalence of PINT or QVT abnormalities and clinical factors were examined. As results, PINT was not changed under 70 years old, then somewhat elevated. QVT elevated from 50 years old. PINT was not associated with QVT. PINT was significantly elevated in NDM and KDM. QVT was elevated in diabetes and hypertension. Among the neuropathic findings, PINT was significantly associated with only pain. By multiple regression analyses, significant aggravating factors of PINT were aging and glucose intolerance. Normal values of PINT were > 0.4 (0.5 (70< years old) Prevalence of PINT abnormality were 3%, 4%, 13% and 9% in N, pre-DM, NDM and KDM, respectively. They were significantly increased with the deterioration of glucose tolerance. QVT abnormality was not significantly increased with glucose intolerance. In conclusion, PINT reflects small nerve fiber function, and associates with DM. So, PINT may be a useful for diagnosis and evaluation of small fiber neuropathy. Disclosure H. Sasaki: None. S. Kishimoto: None. K. Ogawa: None. S. Kurisu: None. K. Nanjo: None. Funding Japan Society for the Promotion of Science

Aims/Introduction The adenosine triphosphate (ATP)-sensitive potassium (KATP) channel is a key component of insulin secretion in pancreatic β-cells. Activating mutations in ABCC8 encoding for the sulfonylurea receptor subunit of the KATP channel have been associated with the development of neonatal diabetes mellitus (NDM). The aim was to investigate clinical and functional characterization of the Pro1198Leu ABCC8 gene mutation associated with permanent NDM (PNDM). Materials and Methods The coding regions and conserved splice sites of KCNJ11, ABCC8 and INS were screened for mutations in a 12-year-old girl diagnosed with PNDM. The functional property of the mutant channel identified was examined with patch-clamp experiments in COS-1 cells. We also investigated the difference of effectiveness between two groups of oral sulfonylureas in vitro and in the patient. Results We identified a heterozygous missense mutation (c.3593 C>T, Pro1198Leu) in ABCC8. The mutated residue (P1198) is located within a putative binding site of sulfonylureas, such as tolbutamide or gliclazide. In patch-clamp experiments, the mutant channel was less ATP sensitive than the wild type. Furthermore, the sensitivity to tolbutamide was also reduced in the mutant channel. In addition to the tolbutamide/gliclazide binding site, glibenclamide is thought to also bind to another site. Glibenclamide was more effective than other sulfonylureas in vitro and in the patient. The treatment of the patient was finally able to be switched from insulin injection to oral glibenclamide. Conclusions We identified the Pro1198Leu ABCC8 mutation in a PNDM patient, and clarified the functional and clinical characterization. The present findings provide new information for understanding PNDM.

Aims/Introduction Although arteriosclerotic diseases have been reported to be frequently complicated by diabetes mellitus (DM), a detailed relationship between hyperglycemia and arterial stiffness has not been fully clarified. We investigated the influence of hyperglycemia on arterial stiffness using the cardio-ankle vascular index (CAVI), which is a new method for estimating arterial stiffness. Materials and Methods CAVI values of 52 early-staged DM patients (duration

Risk factors for cardiovascular complications in Japanese patients with diabetes have not been fully elucidated.Our objective was to determine incidence of and risk factors for coronary heart disease (CHD) and stroke in Japanese diabetic patients.We conducted a prospective study at 59 hospitals throughout Japan.Patients included 940 men and 831 women with type 2 diabetes (mean age, 58.2 yr) without a history of cardiovascular complications who were followed for a median of 7.86 yr.This was an observational study.Incidence of CHD and stroke was evaluated.Incidences of CHD and stroke per 1000 person-years were 9.59 and 7.45, respectively, whereas those of myocardial and brain infarctions were 3.84 and 6.29, respectively. Multivariate Cox analysis revealed that the serum log-transformed triglyceride level was a potent and independent predictor of CHD [hazard ratio (HR) = 1.54; 95% confidence interval (CI) = 1.22-1.94 per 1 sd increase), comparable to low-density lipoprotein (LDL) cholesterol (HR = 1.49; 95% CI = 1.25-1.78 per 1 sd increase). Triglycerides and LDL cholesterol linearly and continuously increased CHD risk, and subjects in the top third for both had markedly high risks of CHD, and their effects were possibly additive. However, serum triglycerides worked independently of blood pressure levels. Systolic blood pressure was the only significant predictor for stroke except for age (HR = 1.31; 95% CI = 1.04-1.65, per 1 sd increase).In Japanese patients with type 2 diabetes, the serum triglyceride level was a leading predictor of CHD, comparable to LDL cholesterol. Because the serum triglyceride level is not a leading predictor of CHD in diabetic subjects in Western countries, ethnic group-specific strategies for prevention of diabetic macroangiopathy may be indicated.

Aims/Introduction: Human islet polypeptide S20G mutation (hIAPPS20G) is associated with earlier onset type 2 diabetes and increased amyloidogenicity and cytotoxicity in vitro vs wild-type hIAPP (hIAPPWT), suggesting that amyloidogenesis may be pathogenic for type 2 diabetes. We compared the contributions of hIAPPS20G and hIAPPWT toward intra islet amyloid formation and development of type 2 diabetes in a unique physiologic knock-in mouse model. Materials and Methods: We replaced the mouse IAPP gene (M allele) with hIAPPWT (W allele) and hIAPPS20G (G allele) via homologous recombination and backbred transgenic mice against C57Bl/6 strain 5 generations to minimize genetic variation. Mice (3 month old) were maintained on control (CD) or high fat diet (HFD) for 15 months and studied at 3 month intervals by oral glucose tolerance testing (OGTT) and pancreas histology to assess glucose homeostastis, amyloidogeneisis, islet mass, β cell replication, and apoptosis. Results: IAPP blood levels were indistinguishable in all mice. WW and GW mice maintained on both diets lacked intraislet amyloid at all ages. On both diets relative to MM controls WW and GW mice exhibit glucose intolerance (P

Aims/Introduction: We have previously reported that the Pro198Leu missense polymorphism in the glutathione peroxidase 1 (GPx-1) gene was associated with frequent macrovascular disease (MVD). Our goal was to examine whether the GPx-1 genotype is associated with diabetic neuropathy. Materials and Methods: We determined the GPx-1 genotype in 173 Japanese type 2 diabetic patients who received medical interviews, physical examinations, nerve conduction studies, quantitative vibratory perception (QVP), head-up tilt and heart rate variability tests by polymerase chain reaction-restriction fragment-length polymorphism. Diabetic sensorimotor distal symmetric polyneuropathy (DSPN) and diabetic autonomic neuropathy (DAN) were evaluated separately. DSPN and DAN were defined by two or more abnormalities of neuropathic leg symptoms, diminished Achilles tendon reflexes or impaired QVP in toes, and two autonomic dysfunctions, respectively. The association of the GPx-1 genotype with DSPN, DAN, MVD and other clinical manifestations was analyzed. Results: The prevalence of DSPN, impaired QVP and painful leg cramps in patients having a genotype with Pro/Leu at the codon 198 (Pro/Leu type) was significantly higher than those with Pro/Pro type. As a result of multivariate analyses that contained the GPx-1 genotype as an independent variable, the Pro/Leu type was extracted as a significant risk factor of DSPN, QVP impairment and MVD. The statistical significance did not disappear, even after proteinuria, retinopathy and a history of MVD were introduced as independent variables. In contrast, the GPx-1 genotype was not associated with DAN. Conclusions: The Pro198Leu missense polymorphism of the GPx-1 gene might have a common genetic predisposition to DSPN and MVD. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00127.x, 2011)

Aims/Introduction: In order to diagnose diabetic symmetric polyneuropathy (DSPN) more simply and accurately, we identified symptoms that correlated with neurological functions and existed more frequently in diabetic than non-diabetic subjects. Materials and Methods: The relationships between 10 symptoms (numbness or paresthesia in toe and sole, numbness in hand, pain in foot or hand, coldness in legs, painful leg cramp, dizziness on standing, sweating restricted to face/trunk and frequent constipation/diarrhea) and clinical background, defined as DSPN and cardiovascular autonomic neuropathy (CAN) by the criteria proposed in the statement of the American Diabetes Association, and seven quantitative nerve function data were evaluated in 593 diabetic patients in Wakayama Medical University Hospital (WMUH). Furthermore, the prevalence of various symptoms was examined by three questionnaires: a WMUH survey (999 diabetic outpatients), a Nationwide survey (1524 male diabetic outpatients under a primary-care physician) and a Control survey (501 non-diabetic subjects). Results: Bilateral ‘numbness in toe and sole’, ‘paresthesia in toe and sole’, ‘pain in foot’ and ‘sweating restricted to face/trunk’ were significantly associated with diabetes duration, retinopathy, probable and confirmed DSPN, possible and advanced CAN, and all or six nerve functions. Questionnaire surveys clarified that symptoms that are not rare (>15%) and more frequent in diabetic than non-diabetic subjects were bilateral ‘numbness in toe and sole’, ‘paresthesia in toe and sole’, ‘coldness in legs’, ‘dizziness on standing’ and ‘sweating restricted to face/trunk’. Conclusions: Therefore, bilateral ‘numbness in toe and sole’, ‘paresthesia in toe and sole’ and ‘sweating restricted to face/trunk’ are suitable symptoms useful for the diagnosis of DSPN. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00124.x, 2011)

Some mutations of the insulin gene cause hyperinsulinemia or hyperproinsulinemia. Replacement of biologically important amino acid leads to defective receptor binding, longer half-life and hyperinsulinemia. Three mutant insulins have been identified: (i) insulin Chicago (F49L or PheB25Leu); (ii) insulin Los Angeles (F48S or PheB24Ser); (iii) and insulin Wakayama (V92L or ValA3Leu). Replacement of amino acid is necessary for proinsulin processing results in hyperproinsulinemia. Four types have been identified: (i) proinsulin Providence (H34D); (ii) proinsulin Tokyo (R89H); (iii) proinsulin Kyoto (R89L); and (iv) proinsulin Oxford (R89P). Three of these are processing site mutations. The mutation of proinsulin Providence, in contrast, is thought to cause sorting abnormality. Compared with normal proinsulin, a significant amount of proinsulin Providence enters the constitutive pathway where processing does not occur. These insulin gene mutations with hyper(pro)insulinemia were very rare, showed only mild diabetes or glucose intolerance, and hyper(pro)insulinemia was the key for their diagnosis. However, this situation changed dramatically after the identification of insulin gene mutations as a cause of neonatal diabetes. This class of insulin gene mutations does not show hyper(pro)insulinemia. Mutations at the cysteine residue or creating a new cysteine will disturb the correct disulfide bonding and proper conformation, and finally will lead to misfolded proinsulin accumulation, endoplasmic reticulum stress and apoptosis of pancreatic β-cells. Maturity-onset diabetes of the young (MODY) or an autoantibody-negative type 1-like phenotype has also been reported. Very recently, recessive mutations with reduced insulin biosynthesis have been reported. The importance of insulin gene mutation in the pathogenesis of diabetes will increase a great deal and give us a new understanding of β-cell biology and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00100.x, 2011).

Introduction: We investigated the effect of Ricetrienol, which is an anti-oxidant extracted from rice bran, and α-tocopherol on the adipocytokine abnormalities and fatty liver in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Materials and Methods: A total of 18 OLETF rats were bred using a 30% sucrose solution (the diabetic group; DM), whereas another 18 OLETF rats were bred using ordinary water (the non-diabetic obese group; OB) as drinking water, respectively. After the sucrose-fed rats developed diabetes, all of the rats from the diabetic and obese groups were randomly divided into three groups. Then each group was fed either standard chow (DM-S, OB-S group), 0.05% Ricetrienol-containing chow (DM-R, OB-R group) or 0.05%α-tocopherol-containing chow (DM-A, OB-A group), respectively. After 12 weeks of feeding, all the rats were killed. Plasma insulin, adiponectin, resistin and leptin were assayed by enzyme immunoassay. Histopathological findings of liver tissue were scored according to Brunt and Kleiner’s method, and triglyceride contents of the liver tissue were investigated. Results: Plasma adiponectin was significantly reduced in DM-S compared with OB-S, but it had significantly increased in DM-R and DM-A as opposed to DM-S. Plasma resistin showed a significant increase in DM-S compared with OB-S, but it was significantly reduced in DM-A than in DM-S. Though the triglyceride contents of liver tissue significantly increased in DM-S as opposed to OB-S, they were significantly reduced in DM-R compared with DM-S. Histopathological scores were significantly higher in DM-S than OB-S. Conclusions: The present study shows that Ricetrienol might prevent adipocytokine abnormalities and fatty liver in OLETF diabetic rats. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00090.x, 2011)

Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long-term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder.

Concept of Diabetes Mellitus: Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long‐term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder.

OBJECTIVE Our goal was to ascertain the prevalence of pruritus in diabetic and nondiabetic subjects and the relevance of symptoms, signs, and nerve functions of diabetic polyneuropathy (DPN) of pruritus. RESEARCH DESIGN AND METHODS A large-scale survey of 2,656 diabetic outpatients and 499 nondiabetic subjects was performed. In diabetic subjects, the relationship between pruritus and age, sex, diabetic duration, A1C, Achilles tendon reflex (ATR), and abnormal sensation in legs was evaluated. In 105 diabetic subjects, nerve conduction studies, quantitative vibratory threshold (QVT), heart rate variability, and a fall of systolic blood pressure at a head-up tilt test (ΔBP) were performed, and the relationships between pruritus and nerve functions were evaluated. RESULTS Although the prevalence of truncal pruritus of unknown origin (TPUO) in diabetic subjects was significantly higher than that in age-matched nondiabetic subjects (11.3 vs. 2.9%, P = 0.0001), the prevalence of other pruritus was not different between the two groups. Multiple logistic regression analysis revealed that abnormal sensation and ATR areflexia were independent risk factors for TPUO in age, sex, duration of diabetes, and A1C. ΔBP in diabetic subjects with TPUO was significantly impaired compared with that in those without TPUO. Larger ΔBP was identified as a significant risk factor of TPUO independent of other nerve dysfunctions by multiple logistic regression analysis. CONCLUSIONS TPUO is significantly more frequent in diabetic than in nondiabetic individuals. TPUO is significantly associated with symptoms and signs of DPN, including impaired blood pressure response in a head-up tilt test. TPUO, therefore, might be a newly recognized symptom of DPN.

Chronic kidney disease (CKD) and metabolic syndrome have been recognized as risk factors for cardiovascular disease. However, there is no information comparing their impact on macroangiopathy in diabetic patients. Thus, we studied the prevalence of CKD and metabolic syndrome in Japanese type 2 diabetic patients and then compared their impact on peripheral arterial disease (PAD) in type 2 diabetic patients.This study focused on Japanese type 2 diabetic patients without hemodialysis (n = 1014). Patients with albuminuria, including microalbuminuria and/or an estimated glomerular filtration rate less than 60 mL/min/1.73(2), were diagnosed as having CKD. PAD was defined as ankle-brachial blood pressure index less than 0.9.The prevalence of CKD and metabolic syndrome was 47.1% and 39.6%, respectively. In four age- and duration-matched groups classified by the presence or absence of CKD and metabolic syndrome, the prevalence of PAD was significantly higher in groups with CKD alone than those with metabolic syndrome alone, and the high prevalence in the groups with CKD was not influenced by the coexistence with metabolic syndrome.This study indicates that CKD has more powerful impact on PAD than metabolic syndrome in type 2 diabetic patients.

The Met55Val polymorphism in the small ubiquitin-like modifier 4 (SUMO4) gene has been associated with susceptibility not only to type 1 diabetes, but also to type 2 diabetes and diabetic nephropathy. We tried to confirm the association with susceptibility to type 2 diabetes and to investigate its role in diabetic vascular complications. The polymorphism was genotyped in two independent Japanese samples (Wakayama and Tokyo) by the TaqMan method. Susceptibility to type 2 diabetes and prevalence of diabetic vascular complications (coronary heart disease, cerebral infarction, retinopathy, and nephropathy) were evaluated by case-control study and multivariate logistic regression analysis, respectively. There were no significant differences in the frequency of alleles or genotypes between patients and controls. The Val allele, however, was associated with higher prevalence of coronary heart disease in patients in both groups (Wakayama, n = 423, odds ratio, 1.64; 95% confidence interval, 1.02–2.64; P = 0.041; Tokyo, n = 451, odds ratio, 1.58; 95% CI, 1.07–2.34; P = 0.021, in an additive model, respectively). No significant associations were observed with other diabetic vascular complications. Although association of the polymorphism with susceptibility to type 2 diabetes or nephropathy was not replicated, an association of the polymorphism with risk of coronary heart disease in type 2 diabetes is suggested.

A novel frameshift mutation attributable to 14-nucleotide insertion in hepatocyte nuclear factor-1alpha (HNF-1alpha) encoding a truncated HNF-1alpha (G554fsX556) with 76-amino acid deletion at its carboxyl terminus was identified in a Thai family with maturity-onset diabetes of the young (MODY). The wild-type and mutant HNF-1alpha proteins were expressed by in vitro transcription and translation (TNT) assay and by transfection in HeLa cells. The wild-type and mutant HNF-1alpha could similarly bind to human glucose-transporter 2 (GLUT2) promoter examined by electrophoretic mobility shift assay (EMSA). However, the transactivation activities of mutant HNF-1alpha on human GLUT2 and rat L-type pyruvate kinase (L-PK) promoters in HeLa cells determined by luciferase reporter assay were reduced to approximately 55-60% of the wild-type protein. These results suggested that the functional defect of novel truncated HNF-1alpha (G554fsX556) on the transactivation of its target-gene promoters would account for the beta-cell dysfunction associated with the pathogenesis of MODY.

Prediction of the disease status is one of the most important objectives of genetic studies. To select the genes with strong evidence of the association with type 2 diabetes mellitus, we validated the associations of the seven candidate loci extracted in our earlier study by genotyping the samples in two independent sample panels. However, except for KCNQ1, the association of none of the remaining seven loci was replicated. We then selected 11 genes, KCNQ1, TCF7L2, CDKAL1, CDKN2A/B, IGF2BP2, SLC30A8, HHEX, GCKR, HNF1B, KCNJ11 and PPARG, whose associations with diabetes have already been reported and replicated either in the literature or in this study in the Japanese population. As no evidence of the gene-gene interaction for any pair of the 11 loci was shown, we constructed a prediction model for the disease using the logistic regression analysis by incorporating the number of the risk alleles for the 11 genes, as well as age, sex and body mass index as independent variables. Cumulative risk assessment showed that the addition of one risk allele resulted in an average increase in the odds for the disease of 1.29 (95% CI=1.25-1.33, P=5.4 x 10(-53)). The area under the receiver operating characteristic curve, an estimate of the power of the prediction model, was 0.72, thereby indicating that our prediction model for type 2 diabetes may not be so useful but has some value. Incorporation of data from additional risk loci is most likely to increase the predictive power.

We carried out a multistage genome-wide association study of type 2 diabetes mellitus in Japanese individuals, with a total of 1,612 cases and 1,424 controls and 100,000 SNPs. The most significant association was obtained with SNPs in KCNQ1, and dense mapping within the gene revealed that rs2237892 in intron 15 showed the lowest P value (6.7 x 10(-13), odds ratio (OR) = 1.49). The association of KCNQ1 with type 2 diabetes was replicated in populations of Korean, Chinese and European ancestry as well as in two independent Japanese populations, and meta-analysis with a total of 19,930 individuals (9,569 cases and 10,361 controls) yielded a P value of 1.7 x 10(-42) (OR = 1.40; 95% CI = 1.34-1.47) for rs2237892. Among control subjects, the risk allele of this polymorphism was associated with impairment of insulin secretion according to the homeostasis model assessment of beta-cell function or the corrected insulin response. Our data thus implicate KCNQ1 as a diabetes susceptibility gene in groups of different ancestries.

Although brachial-ankle pulse wave velocity (baPWV) is a non-invasive method of detecting arteriosclerosis, it is affected by changes in blood pressure (BP). Cardio-ankle vascular index (CAVI) is a new method for estimating arteriosclerosis, and it has been reported to be less influenced by BP. We investigated the influence of BP changes on CAVI and the correlation of CAVI to clinical factors and carotid arteriosclerosis. CAVI and baPWV in 35 non-diabetic and 33 diabetic subjects were measured in increased BP (after stair climbing) and rested BP (after 10min of rest). Intima-media thickness (IMT) of carotid arteries was measured by ultrasoundsonography. We achieved the following results: CAVI did not show a significant change with a change in BP in both non-diabetic and diabetic subjects. On the contrary, baPWV was significantly influenced by BP changes. Carotid artery IMT had a significant positive correlation with CAVI and baPWV. Multiple regression analysis revealed that significant risk factors of high baPWV were age and systolic BP. On the contrary, significant risk factors of high CAVI were age and hemoglobin A1c, while systolic BP was not relevant. Our findings suggest that CAVI is independent of BP and useful as an indicator of early arteriosclerosis in diabetic subjects.

This multinational study was conducted to investigate the association between a mitochondrial DNA (mtDNA) T16189C polymorphism and type 2 diabetes in Asians. The mtDNA 16189C variant has been reported to be associated with insulin resistance and type 2 diabetes. However, a recent meta-analysis concluded that it is negatively associated with type 2 diabetes in Europids. Since the phenotype of an mtDNA mutant may be influenced by environmental factors and ethnic differences in the nuclear and mitochondrial genomes, we investigated the association between the 16189C variant and type 2 diabetes in Asians.The presence of the mtDNA 16189C variant was determined in 2,469 patients with type 2 diabetes and 1,205 non-diabetic individuals from Korea, Japan, Taiwan, Hong Kong and China. An additional meta-analysis including previously published Asian studies was performed. Since mtDNA nucleotide position 16189 is very close to the mtDNA origin of replication, we performed DNA-linked affinity chromatography and reverse-phase liquid chromatography/tandem mass spectrometry and chromatin immunoprecipitation to identify protein bound to the 16189 region.Analysis of participants from five Asian countries confirmed the association between the 16189C variant and type 2 diabetes [odds ratio (OR) 1.256, 95% CI 1.08-1.46, p=0.003]. Inclusion of data from three previously published Asian studies (type 2 diabetes n=3,283, controls n=2,176) in a meta-analysis showed similar results (OR 1.335, 95% CI 1.18-1.51, p=0.000003). Mitochondrial single-stranded DNA-binding protein (mtSSB) was identified as a candidate protein bound to the 16189 region. Chromatin immunoprecipitation in cybrid cells showed that mtSSB has a lower binding affinity for the 16189C variant than the wild-type sequence.The mtDNA 16189C variant is associated with an increased risk of type 2 diabetes in Asians.

Prevalence of metabolic syndrome (MetS) in type 2 diabetes and its association with vascular complications were studied in 637 Japanese type 2 diabetic patients. MetS was diagnosed using criteria proposed by the Japanese study group for the definition of MetS in 2005. The prevalence of MetS in patients studied was higher in males (45.9%) than females (28.0%). The prevalence of MetS was 53.0% in males and 35.4% in females in patients with duration of less than 10 years, and decreased with an increase in duration. Upon comparing patients groups complicated with and without MetS, we determined the MetS group had significantly higher levels of fasting serum C-peptide and high-sensitivity C-reactive protein, and a significantly lower level of serum adiponectin. However, the prevalence of coronary heart disease, brain infarction, or peripheral arterial disease was not significantly different between these groups. On the other hand, the prevalence of microangiopathy in the group with MetS was significantly higher than in that without MetS, and became significantly higher along with an increase in duration. This study clarifies the prevalence of MetS in Japanese type 2 diabetic patients, and suggests that MetS is associated with microangiopathy rather than macroangiopathy in Japanese type 2 diabetic patients.

Context: A genome-wide association study in the French population has detected that novel single-nucleotide polymorphisms (SNPs) in the IDE-KIF11-HHEX gene locus and the SLC30A8 gene locus are associated with susceptibility to type 2 diabetes. Objective: We investigated whether SNPs in these loci were associated with type 2 diabetes in Japanese. Design: Two SNPs, rs7923837 and rs1111875, in the IDE-KIF11-HHEX gene locus and one SNP, rs13266634, in the SLC30A8 gene locus were genotyped in Japanese type 2 diabetic patients (n = 405) and in nondiabetic control subjects (n = 340) using the TaqMan genotyping assay system. Results: The G allele of rs7923837 was associated with type 2 diabetes [odds ratio 1.66, 95% confidence interval (CI) 1.28–2.15; P = 0.00014], following the same tendency as in the French population of the previous report. Heterozygous and homozygous carriers of the risk allele had odds ratios of 1.57 (95% CI 1.15–2.16; P = 0.0050) and 3.16 (95% CI 1.40–7.16; P = 0.0038) relative to noncarriers. Although the G allele was a major allele (66.5%) in the French population, it was a minor allele (23.8%) in Japanese. The G allele of rs1111875 was also associated with type 2 diabetes (odds ratio 1.42, 95% CI 1.13–1.78; P = 0.0024). Heterozygous and homozygous carriers of the risk allele had odds ratios of 1.31 (95% CI 0.97–1.77; P = 0.0810) and 2.40 (95% CI 1.34–4.32; P = 0.0028) relative to noncarriers. A significant association with type 2 diabetes was not observed for rs13266634. Conclusions: Polymorphisms in the IDE-KIF11-HHEX gene locus are associated with susceptibility to type 2 diabetes across the boundary of race.

Transcription factor 7-like 2 (TCF7L2) has been shown to be associated with type 2 diabetes mellitus in multiple ethnic groups. Regarding the Asian population, Horikoshi et al. (Diabetologia 50:747-751, 2007) and Hayashi et al. (Diabetologia 50:980-984, 2007) reported that single nucleotide polymorphisms (SNPs) in TCF7L2 were associated with type 2 diabetes in the Japanese population, while contradictory results were reported for Han Chinese populations. The aim of this study was to investigate the associations of the TCF7L2 gene with type 2 diabetes using a relatively large sample size: 2,214 Japanese individuals with type 2 diabetes and 1,873 normal controls. The minor alleles of rs7903146, rs11196205, and rs12255372 showed significant associations with type 2 diabetes (OR=1.48, P=2.7 x 10(-4); OR=1.39, P=4.6 x 10(-4); OR=1.70, P=9.8 x 10(-5), respectively) in the combined sample sets. However, neither rs11196218 nor rs290487 showed a significant association. These results indicate that TCF7L2 is an important susceptibility gene for type 2 diabetes in the Japanese population.

Circulating adiponectin (ADP) level in diabetic patients was mainly studied from a viewpoint of insulin action, with little being known about the regulation by pancreatic beta-cell function. We thus investigated the relationship between the serum ADP concentration and pancreatic beta-cell function in non-obese [body mass index (BMI)30 kg/m(2)] diabetic patients. Serum ADP was measured in 239 type 2 diabetic patients, 61 type 1 diabetic patients and 159 non-obese and non-diabetic subjects with enzyme-linked immunosorbent assay. Serum ADP was analyzed separately by gender. In both males and females, the ADP level increased in conjugation with beta-cell dysfunction, estimated by fasting serum C-peptide, and showed marked increase in type 1 diabetic patients. Multivariate analysis in type 2 diabetic patients showed that the fasting serum C-peptide was extracted as an independent and significantly negative modulator for serum ADP in addition to BMI. The ADP level was not associated with the daily dose of injected insulin in the multivariate analysis using insulin treated patients with types 1 and 2 diabetes. These results indicate that pancreatic beta-cell function is one of a significant negative modulator for the circulating ADP level in non-obese diabetic patients and support the presence of an adipoinsular axis.

Glucose transporter (GLUT) 4 plays an important role in insulin-induced glucose uptake in skeletal muscle and white adipose tissue. Although GLUT4 is abundant in the hypothalamus as well as in these peripheral tissues, little is known about the role of GLUT4 in the hypothalamus. In this study, we examined the subcellular localization of GLUT4 and the activation of insulin signaling pathways in the hypothalamic arcuate nucleus of ob/ob mice under basal conditions. The expression of GLUT4 in the arcuate nucleus of ob/ob mice was higher than that in lean mice. Interestingly, GLUT4 on the plasma membrane increased significantly in neurons of the arcuate nucleus of ob/ob mice when compared to that in lean mice. Because serum insulin levels of ob/ob mice were very high, we hypothesized that insulin strongly stimulates GLUT4 translocation in the arcuate nucleus of ob/ob mice. Unexpectedly, tyrosine phosphorylation of IR and insulin receptor substrate-1 (IRS-1) was faint in the hypothalamus of lean and ob/ob mice. In addition, phosphorylation of IRS-1 at Ser307 in the hypothalamus of ob/ob mice was higher when compared to that in lean mice, suggesting that insulin signaling is impaired by phosphorylation of IRS-1 at Ser307 in the hypothalamus of ob/ob mice. However, serine phosphorylation of Akt in the arcuate nucleus of ob/ob mice increased significantly when compared to that in lean mice. Furthermore, the expression of brain-derived neurotrophic factor, an activator of PI3K-Akt pathway in neurons, increased significantly in the ventromedial hypothalamus of ob/ob mice. We discuss the possibility of novel pathways which induce the translocation of GLUT4 in the arcuate nucleus of ob/ob mice.

Betacellulin (BTC), a member of the epidermal growth factor (EGF) family, is an important factor in the growth and/or differentiation of pancreatic β cells. In this point of view, we determined the transcriptional start site of the human BTC gene and screened the protein-coding region for mutations. The transcriptional start site was located 347 bp upstream from the translational initiation codon. After screening the protein coding exons (exons 1–5), we identified two novel missense mutations, Cys (TGC) to Gly (GGC) at codon 7 ( C7G ) and Leu (TTG) to Met (ATG) at codon 124 ( L124M ), and a single nucleotide substitution (− 31c/t ) in the intron 2. The C7G was located in the signal peptide and the L124M in the transmembrane domain and this Leu at codon 124 was conserved among human, bovine, rat, and mouse. The frequencies of these variants, however, were similar between type 2 diabetic patients ( n = 228) and non-diabetic control subjects ( n = 170). These data suggest that genetic variations in the protein-coding region of the human BTC gene are unlikely to be a major contributor to development of type 2 diabetes.

As a westernized lifestyle becomes widespread in Japan, the number of individuals with obesity, as well as type 2 diabetes, is rapidly increasing. In this investigation, we studied the prevalence of obesity and its association with the development of diabetic macroangiopathy and microangiopathy. The clinical records of 634 patients in our hospital with type 2 diabetes were surveyed. The relationship between obesity and diabetic retinopathy and nephropathy and macroangiopathy (carotid artery intima-media thickness, IMT) was examined using univariate and multivariate analysis. A body mass index (BMI) ≥ 25 kg/m 2 was used as the diagnostic criterion for obesity. The prevalence of obesity at the time of the survey was 35% and a history of obesity was reported in 70% of the survey population. Multiple regression analysis revealed that the maximum BMI was significantly correlated with IMT thickening. The prevalence of nephropathy in previously obese patients was significantly higher than in non-obese patients. The maximum BMI was significantly associated with the development of retinopathy and nephropathy, as shown by logistic regression analysis. This suggests that a history of obesity may be an important risk factor for the development of micro- and macroangiopathy in Japanese with type 2 diabetes.

The discriminating abilities of fasting plasma glucose (FPG) and HbA1c were compared on screening tests for impaired glucose tolerance (IGT) and IGT plus diabetes mellitus by the receiver operating characteristic (ROC) curve analysis. Furthermore, effects of sex, age and BMI were examined on sensitivity and specificity of the optimal cutoff points. This study included 997 subjects who were recruited for 75 g OGTT after the first screening of the Japan Diabetes Prevention Program. According to the 1997 criteria of the American Diabetes Association (ADA), 140 subjects were classified as diabetic and 256 as IGT. The areas under the ROC curves of FPG were significantly larger than those of HbA1c. The optimal cutoff points of FPG were 102 mg/dl for IGT and 105 mg/dl for IGT plus diabetes mellitus. Those of HbA1c were both 5.3%. In screening with FPG, females had significantly lower sensitivity and higher specificity than males, and the specificity for IGT plus diabetes mellitus was the lowest in the obese group. In screening with HbA1c, the specificity was low in the older and the obese groups. We concluded that FPG was superior to HbA1c for screening of IGT and IGT plus diabetes mellitus and the optimal cutoff point of FPG would be 102 mg/dl or greater.

Common uncoupling protein 2 (UCP2) promoter polymorphism −866G/A is reported to be associated with its expression in adipose tissue and the risk of obesity in Caucasians. On the other hand, several studies suggested that UCP2 expression in β-cells is an important determinant of insulin secretion. In the Japanese population, morbid obesity is very rare, and insulin secretion capacity is relatively low as compared with Caucasians. Because UCP2 would link to insulin secretion and obesity, it might explain this ethnic difference. Here, we report that the UCP2 promoter with the A allele showed higher promoter activity in the INS-1 β-cell line. The frequency of the A allele is higher in our Japanese study than that in Caucasians. Type 2 diabetic patients with the A allele need insulin therapy earlier and showed higher frequency of insulin treatment. Moreover glucose-induced early insulin secretion is significantly lower in patients with the A allele. However, there was no difference in allele frequency between obese and lean type 2 diabetic patients. In conclusion, UCP2 promoter polymorphism −866G/A does not affect obesity in Japanese type 2 diabetic patients but affects its transcription in β-cells and modulates glucose-induced insulin secretion and eventually insulin requirement in Japanese type 2 diabetic patients. Higher A allele frequency in the Japanese population might partly explain the ethnic difference of insulin secretion capacity.

2型糖尿病における東洋医学の証と西洋医学的な臨床指標との関連性を明確にするために, 2型糖尿病患者の陰陽証あるいは虚実証の頻度ならびに各証とインスリン抵抗性 (IR) との関連性を検討した。65名の2型糖尿病患者 [男性27名 (平均年齢60.9±12.0歳), 女性38名 (64.9±8.4歳)] を陰陽証あるいは虚実証単独で分類した場合の頻度は, 陰証30.8%, 中間証32.3%, 陽証36.9%あるいは虚証30.8%, 中間証33.8%, 実証35.4%であった。また, 陰陽・虚実証を併用した分類における頻度は陽実証26.2%, 中間中間証21.5%, 陰虚証18.5%, 陽虚証10.8%, 中間実証7.7%, 陽中間証6.2%, 陰中間証6.2%, 中間虚証3.1%であった。一方, インスリン療法を除く2型糖尿病患者についてIRの指標である空腹時血漿インスリン値 (fasting plasma insulin level: F-IRI) と Homeostasis Model Assessment によるインスリン抵抗性指標 (HOMA-IR) を検討すると, F-IRIは実証群が虚証群 (p=0.044) に比し, 陽実証群が陰虚証群 (p=0.033) に比し有意な高値, HOMA-IRは陽実証群が陰虚証群に比し有意な (p=0.017) 高値であった。以上より2型糖尿病患者では陽証と陰証, 実証と虚証が同程度存在することが確認された。さらに, 陽証や実証を呈する2型糖尿病患者ではIRとの関連性を有することが示唆された。

We report a 60-year-old woman with neurosarcoidosis. She was referred to our hospital for examination of the cause of pain in left Th4-6 dermatome. Chest X-ray and computed tomography (CT) revealed bilateral hilar and mediastinal lymphadenopathy, and her serum angiotensin converting enzyme (ACE) level was elevated. Histological finding of mediastinal lymph nodes consisted with sarcoidosis. Therefore, her pain was thought to be spinal root pain caused by neurosarcoidosis. With the administration of prednisolone, her symptom and bilateral hilar lymphadenopathy disappeared, and serum ACE level became normal. It is important to pay attention to neurosarcoidosis when patients show unknown spinal root symptom, although it is rare.

Diabetes mellitus with the mitochondrial DNA 3243(A-G) mutation is reported to represent 0.5-2.8% of the general diabetic population. Since the characterization of diabetes with the mutation is still incomplete, we undertook a nation-wide case-finding study of genetically defined patients using questionnaires in Japan. One hundred and thirteen Japanese diabetic patients with the mutation were registered and analyzed. The patients had a high prevalence of maternal inheritance of diabetes and deafness, short and thin stature, and showed an early middle-aged onset of diabetes and deafness. Eighty-six percent of the patients required insulin therapy due to the progressive insulin secretory defect. Glucose intolerance of the mothers was associated with an early middle-aged onset of diabetes, reduction in the insulin secretory capacity, early requirement of insulin therapy, and increases in the daily insulin dose. The heteroplasmic concentrations of the 3243 mutation in leukocytes were low and declined with aging. The patients had advanced microvascular complications, and mitochondria-related complications such as cardiomyopathy, cardiac conductance disorders, neuromuscular symptoms, neuropsychiatric disturbance, and macular pattern dystrophy. Thus, this study has revealed that: (1) diabetes mellitus with the 3243 mutation is a subtype of diabetes mellitus with mitochondria-related complications; and (2) insulin secretory ability is more severely impaired in the patients whose mothers were glucose intolerance.

Some mutations of the insulin gene cause hyperinsulinemia or hyperproinsulinemia. Replacement of biologically important amino acid leads to defective receptor binding, longer half‐life and hyperinsulinemia. Three mutant insulins have been identified: (i) insulin Chicago (F49L or PheB25Leu); (ii) insulin Los Angeles (F48S or PheB24Ser); (iii) and insulin Wakayama (V92L or ValA3Leu). Replacement of amino acid is necessary for proinsulin processing results in hyperproinsulinemia. Four types have been identified: (i) proinsulin Providence (H34D); (ii) proinsulin Tokyo (R89H); (iii) proinsulin Kyoto (R89L); and (iv) proinsulin Oxford (R89P). Three of these are processing site mutations. The mutation of proinsulin Providence, in contrast, is thought to cause sorting abnormality. Compared with normal proinsulin, a significant amount of proinsulin Providence enters the constitutive pathway where processing does not occur. These insulin gene mutations with hyper(pro)insulinemia were very rare, showed only mild diabetes or glucose intolerance, and hyper(pro)insulinemia was the key for their diagnosis. However, this situation changed dramatically after the identification of insulin gene mutations as a cause of neonatal diabetes. This class of insulin gene mutations does not show hyper(pro)insulinemia. Mutations at the cysteine residue or creating a new cysteine will disturb the correct disulfide bonding and proper conformation, and finally will lead to misfolded proinsulin accumulation, endoplasmic reticulum stress and apoptosis of pancreatic β‐cells. Maturity‐onset diabetes of the young (MODY) or an autoantibody‐negative type 1‐like phenotype has also been reported. Very recently, recessive mutations with reduced insulin biosynthesis have been reported. The importance of insulin gene mutation in the pathogenesis of diabetes will increase a great deal and give us a new understanding of β‐cell biology and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00100.x, 2011)

Introduction: We investigated the effect of Ricetrienol, which is an anti‐oxidant extracted from rice bran, and α‐tocopherol on the adipocytokine abnormalities and fatty liver in Otsuka Long‐Evans Tokushima Fatty (OLETF) rats. Materials and Methods: A total of 18 OLETF rats were bred using a 30% sucrose solution (the diabetic group; DM), whereas another 18 OLETF rats were bred using ordinary water (the non‐diabetic obese group; OB) as drinking water, respectively. After the sucrose‐fed rats developed diabetes, all of the rats from the diabetic and obese groups were randomly divided into three groups. Then each group was fed either standard chow (DM‐S, OB‐S group), 0.05% Ricetrienol‐containing chow (DM‐R, OB‐R group) or 0.05%α‐tocopherol‐containing chow (DM‐A, OB‐A group), respectively. After 12 weeks of feeding, all the rats were killed. Plasma insulin, adiponectin, resistin and leptin were assayed by enzyme immunoassay. Histopathological findings of liver tissue were scored according to Brunt and Kleiner’s method, and triglyceride contents of the liver tissue were investigated. Results: Plasma adiponectin was significantly reduced in DM‐S compared with OB‐S, but it had significantly increased in DM‐R and DM‐A as opposed to DM‐S. Plasma resistin showed a significant increase in DM‐S compared with OB‐S, but it was significantly reduced in DM‐A than in DM‐S. Though the triglyceride contents of liver tissue significantly increased in DM‐S as opposed to OB‐S, they were significantly reduced in DM‐R compared with DM‐S. Histopathological scores were significantly higher in DM‐S than OB‐S. Conclusions: The present study shows that Ricetrienol might prevent adipocytokine abnormalities and fatty liver in OLETF diabetic rats. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00090.x, 2011)

Aims/Introduction: Human islet polypeptide S20G mutation (hIAPPS20G) is associated with earlier onset type 2 diabetes and increased amyloidogenicity and cytotoxicity in vitro vs wild‐type hIAPP (hIAPPWT), suggesting that amyloidogenesis may be pathogenic for type 2 diabetes. We compared the contributions of hIAPPS20G and hIAPPWT toward intra islet amyloid formation and development of type 2 diabetes in a unique physiologic knock‐in mouse model. Materials and Methods: We replaced the mouse IAPP gene (M allele) with hIAPPWT (W allele) and hIAPPS20G (G allele) via homologous recombination and backbred transgenic mice against C57Bl/6 strain 5 generations to minimize genetic variation. Mice (3 month old) were maintained on control (CD) or high fat diet (HFD) for 15 months and studied at 3 month intervals by oral glucose tolerance testing (OGTT) and pancreas histology to assess glucose homeostastis, amyloidogeneisis, islet mass, β cell replication, and apoptosis. Results: IAPP blood levels were indistinguishable in all mice. WW and GW mice maintained on both diets lacked intraislet amyloid at all ages. On both diets relative to MM controls WW and GW mice exhibit glucose intolerance (P

Concept of Diabetes Mellitus: Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long‐term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder. Classification (Tables 1 and 2, and Figure 1): Table 1 Etiological classification of diabetes mellitus and glucose metabolism disorders I. Type 1 (destruction of pancreatic β‐cells, usually leading to absolute insulin deficiency) A. Autoimmune B. Idiopathic II. Type 2 (ranging from predominantly insulin secretory defect, to predominantly insulin resistance with varying degrees of insulin secretory defect) III. Due to other specific mechanisms or diseases (see Table 2 for details) A. Those in which specific mutations have been identified as a cause of genetic susceptibility (1) Genetic abnormalities of pancreatic β‐cell function (2) Genetic abnormalities of insulin action B. Those associated with other diseases or conditions (1) Diseases of exocrine pancreas (2) Endocrine diseases (3) Liver disease (4) Drug‐ or chemical‐induced (5) Infections (6) Rare forms of immune‐mediated diabetes (7) Various genetic syndromes often associated with diabetes IV. Gestational diabetes mellitus Note: Those that cannot at present be classified as any of the above are called unclassifiable. The occurrence of diabetes‐specific complications has not been confirmed in some of these conditions. Table 2 Diabetes mellitus and glucose metabolism disorders due to other specific mechanisms and diseases A. Those in which specific mutations have been identified as a cause of genetic susceptibility B. Those associated with other diseases or conditions (1) Genetic abnormalities of pancreatic β‐cell function Insulin gene (abnormal insulinemia, abnormal proinsulinemia, neonatal diabetes mellitus) HNF 4α gene (MODY1) Glucokinase gene (MODY2) HNF 1α gene (MODY3) IPF‐1 gene (MODY4) HNF 1β gene (MODY5) Mitochondria DNA (MIDD) NeuroD1 gene (MODY6) Kir6.2 gene (neonatal diabetes mellitus) SUR1 gene (neonatal diabetes mellitus) Amylin Others (2) Genetic abnormalities of insulin action Insulin receptor gene (type A insulin resistance, leprechaunism, Rabson–Mendenhall syndrome etc.) Others (1) Diseases of exocrine pancreas Pancreatitis Trauma/pancreatectomy Neoplasm Hemochromatosis Others (2) Endocrine diseases Cushing’s syndrome Acromegaly Pheochromocytoma Glucagonoma Aldosteronism Hyperthyroidism Somatostatinoma Others (3) Liver disease Chronic hepatitis Liver cirrhosis Others (4) Drug‐ or chemical‐induced Glucocorticoids Interferon Others (5) Infections Congenital rubella Cytomegalovirus Others (6) Rare forms of immune‐mediated diabetes Anti‐insulin receptor antibodies Stiffman syndrome Insulin autoimmune syndrome Others (7) Various genetic syndromes often associated with diabetes Down syndrome Prader‐Willi syndrome Turner syndrome Klinefelter syndrome Werner syndrome Wolfram syndrome Ceruloplasmin deficiency Lipoatrophic diabetes mellitus Myotonic dystrophy Friedreich ataxia Laurence‐Moon‐Biedl syndrome Others The occurrence of diabetes‐specific complications has not been confirmed in some of these conditions. Figure 1 A scheme of the relationship between etiology (mechanism) and patho‐physiological stages (states) of diabetes mellitus. Arrows pointing right represent worsening of glucose metabolism disorders (including onset of diabetes mellitus). Among the arrow lines, indicates the condition classified as ‘diabetes mellitus’. Arrows pointing left represent improvement in the glucose metabolism disorder. The broken lines indicate events of low frequency. For example, in type 2 diabetes mellitus, infection can lead to ketoacidosis and require temporary insulin treatment for survival. Also, once diabetes mellitus has developed, it is treated as diabetes mellitus regardless of improvement in glucose metabolism, therefore, the arrow lines pointing left are filled in black. In such cases, a broken line is used, because complete normalization of glucose metabolism is rare. image The classification of glucose metabolism disorders is principally derived from etiology, and includes staging of pathophysiology based on the degree of deficiency of insulin action. These disorders are classified into four groups: (i) type 1 diabetes mellitus; (ii) type 2 diabetes mellitus; (iii) diabetes mellitus due to other specific mechanisms or diseases; and (iv) gestational diabetes mellitus. Type 1 diabetes is characterized by destruction of pancreatic β‐cells. Type 2 diabetes is characterized by combinations of decreased insulin secretion and decreased insulin sensitivity (insulin resistance). Glucose metabolism disorders in category (iii) are divided into two subgroups; subgroup A is diabetes in which a genetic abnormality has been identified, and subgroup B is diabetes associated with other pathologic disorders or clinical conditions. The staging of glucose metabolism includes normal, borderline and diabetic stages depending on the degree of hyperglycemia occurring as a result of the lack of insulin action or clinical condition. The diabetic stage is then subdivided into three substages: non‐insulin‐ requiring, insulin‐requiring for glycemic control, and insulin‐dependent for survival. The two former conditions are called non‐insulin‐dependent diabetes and the latter is known as insulin‐dependent diabetes. In each individual, these stages may vary according to the deterioration or the improvement of the metabolic state, either spontaneously or by treatment. Diagnosis (Tables 3–7 and Figure 2): Table 3 Criteria of fasting plasma glucose levels and 75 g oral glucose tolerance test 2‐h value Normal range Diabetic range Fasting value

Pax4 is one of the transcription factors that play an important role in the differentiation of islet β-cells. We scanned the Pax4 gene in 200 unrelated Japanese type 2 diabetic patients and found a missense mutation (R121W) in 6 heterozygous patients and 1 homozygous patient (mutant allele frequency 2.0%). The mutation was not found in 161 nondiabetic subjects. The R121W mutation was located in the paired domain and was thought to affect its transcription activity through lack of DNA binding. Six of seven patients had family history of diabetes or impaired glucose tolerance, and four of seven had transient insulin therapy at the onset. One of them, a homozygous carrier, had relatively early onset diabetes and slowly fell into an insulin-dependent state without an autoimmune-mediated process. This is the first report of a Pax4 gene mutation that exhibits loss of function and seems to be associated with type 2 diabetes. This work provides significant implications for the Pax4 gene as one of the predisposing genes for type 2 diabetes in the Japanese.

The allele frequencies for a Pro 12 →Ala substitution in peroxisome proliferator–activated receptor-γ differ among ethnic groups, and its relationship with diabetes and associated diseases is controversial. The prevalence of this polymorphism and its effects on clinical characteristics have now been evaluated with a large number of Japanese individuals with type 2 diabetes ( n = 2,201) and normal control subjects ( n = 1,212) recruited by 10 institutions located in seven different cities in Japan. The allele frequency for the Ala 12 variant was significantly lower in the type 2 diabetic group than in the control group (2.39 vs. 4.13%, P = 0.000054). However, compared with subjects without the Ala 12 variant, the diabetic subjects with this variant exhibited a significantly higher serum concentration of total cholesterol ( P = 0.001), manifested a reduced capacity for insulin secretion as evaluated by homeostasis model assessment ( P = 0.007), and tended to possess a higher level of HbA 1c . These data suggest that the Ala 12 variant is associated with a reduced risk for the development of diabetes in the general population, but that it may be also a risk factor for insulin deficiency and disease severity in individuals with type 2 diabetes.

Islet amyloid polypeptide (IAPP, "amylin") is the amyloid-fibril-forming polypeptide in the islets of Langerhans associated with type 2 diabetes mellitus. A missense mutation in the IAPP gene associated with early-onset type 2 diabetes has been identified in the Japanese population. This mutation results in a glycine for serine substitution at position 20 of the mature IAPP molecule. Whether or not formation of islet amyloid with resulting destruction of islet tissue is the cause of this diabetes is yet not known. The present in vitro study was performed in order to investigate any influence of the amino acid substitution on the fibril formation capacity. Synthetic full-length wild type (IAPPwt) and mutant (IAPPS20G) as well as corresponding truncated peptides (position 18-29) were dissolved in dimethylsulfoxide (DMSO) or in 10% acetic acid at a concentration of 10 mg/mL and their fibril forming capacity was checked by Congo red staining, electron microscopy, a Congo red affinity assay and Thioflavine Tfluorometric assay. It was found that full-length and truncated IAPPS20G both formed more amyloid-like fibrils and did this faster compared to IAPPwt. The fibril morphology differed slightly between the preparations.The amino acid substitution (S20G) is situated close to the region of the IAPP molecule implicated in the IAPP fibrillogenesis. The significantly increased formation of amyloid-like fibrils by IAPPS20G is highly interesting and may be associated with an increased islet amyloid formation in vivo and of fundamental importance in the pathogenesis of this specific form of diabetes.