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The predicted structures of major proteins involved in the insulin signaling pathway obtained from the AlphaFold Protein Structure Database.

Aim The aim of this prospective cohort study was to evaluate the risk factors for postpartum glucose intolerance (GI) in women with gestational diabetes mellitus (GDM). Method A total of 140 women with GDM were enrolled. Of these, 115 underwent a 75-g oral glucose tolerance test (OGTT) at 12 weeks after delivery. Clinical factors and parameters in the antepartum 75-g OGTT associated with postpartum GI were evaluated by logistic regression analyses. Results Twenty-two (19.1%) of the 115 women with GDM developed postpartum GI. The univariate and multivariable logistic regression analyses revealed that low oral disposition index (DI) was a risk factor for postpartum GI (OR, 0.2; 95% CI, 0.04-0.7; p < 0.05), and that no clinical factors were associated with postpartum GI. Conclusions Lower oral DI on the antepartum 75-g OGTT may be a useful marker for identifying GDM women who are at high risk for postpartum GI.

Aims/Introduction Brown adipose tissue (BAT) utilizes large amounts of fuel for thermogenesis, but the mechanism by which fuel substrates are switched in response to changes in energy status is poorly understood. We have now investigated the role of Kruppel‐like factor 15 (KLF15), a transcription factor expressed at a high level in adipose tissue, in the regulation of fuel utilization in BAT. Materials and Methods Depletion or overexpression of KLF15 in HB2 differentiated brown adipocytes was achieved by adenoviral infection. Glucose and fatty acid oxidation were measured with radioactive substrates, pyruvate dehydrogenase complex activity was determined with a colorimetric assay, and gene expression was examined by reverse transcription and real‐time polymerase chain reaction analysis. Results Knockdown of KLF15 in HB2 cells attenuated fatty acid oxidation in association with downregulation of the expression of genes related to this process including Acox1 and Fatp1, whereas it increased glucose oxidation. Expression of the gene for pyruvate dehydrogenase kinase 4 (PDK4), a negative regulator of pyruvate dehydrogenase complex, was increased or decreased by KLF15 overexpression or knockdown, respectively, in HB2 cells, with these changes being accompanied by a respective decrease or increase in pyruvate dehydrogenase complex activity. Chromatin immunoprecipitation showed that Pdk4 is a direct target of KLF15 in HB2 cells. Finally, fasting increased expression of KLf15, Pdk4 and genes involved in fatty acid utilization in BAT of mice, whereas refeeding suppressed Klf15 and Pdk4 expression. Conclusions Our results implicate KLF15 in the regulation of fuel switching between glucose and fatty acids in response to changes in energy status in BAT., Brown adipose tissue (BAT) utilizes large amounts of fuel for thermogenesis with fatty acids and glucose being the major substrates for this process, but the mechanism by which fuel substrates are switched in response to changes in energy status is poorly understood. We here show that KLF15 increases fatty acid oxidation through the regulation of genes related to fatty acid utilization, whereas this transcription factor inhibits glucose oxidation via direct up‐regulation of PDK4 expression and attenuation of PDC activity, in HB2 differentiated brown adipocytes. Given that KLF15 expression in BAT was up‐regulated in response to fasting and down‐regulated after subsequent refeeding in mice and that these changes were accompanied by alterations in the expression of genes related to glucose and lipid utilization, KLF15 might play an important role in the regulation of fuel switching between glucose and fatty acids in response to changes in energy status in BAT.

Aims Whereas homeostasis model assessment of insulin resistance (HOMA‐IR), an easily measured but limited index of insulin resistance, has been shown to correlate with impairment of cardiac function in individuals without diabetes, the pathological relevance of insulin resistance to the development of cardiac dysfunction in individuals with type 2 diabetes has remained unclear. Here we investigated the relation between left ventricular (LV) function as assessed by echocardiography and insulin resistance as evaluated by hyperinsulinemic‐euglycemic clamp analysis, the gold standard for measurement of this parameter, in individuals with type 2 diabetes. Methods This retrospective study included 34 individuals with type 2 diabetes who underwent both hyperinsulinemic‐euglycemic clamp analysis and echocardiography. Both the insulin sensitivity index (ISI) as determined by glucose clamp analysis as well as HOMA‐IR were determined as measures of insulin resistance. The ratio of the peak early‐ to late‐diastolic mitral inflow velocities (E/A) and the LV ejection fraction (LVEF) were determined as measures of diastolic and systolic function, respectively. Results The ISI was significantly correlated with both the E/A ratio and LVEF (correlation coefficients of 0.480 and 0.360, respectively), whereas HOMA‐IR was not correlated with either cardiac parameter. Multivariate analysis revealed that ISI was an independent predictor for both a high log [E/A] (P = 0.031) and a high LVEF (P = 0.045). Conclusions Insulin resistance as evaluated by hyperinsulinemic‐euglycemic clamp analysis may be causally related to LV diastolic and systolic dysfunction in individuals with type 2 diabetes., Our study suggested that insulin resistance as evaluated by glucose clamp analysis is associated with LV diastolic and systolic dysfunction in individuals with type 2 diabetes.

Aims/Introduction We investigated the effect of FreeStyle LibreTM on glycemic control in Japanese type 2 diabetes patients treated with basal–bolus insulin therapy. Materials and Methods This prospective, 90‐day single‐arm study enrolled 94 adults with type 2 diabetes treated with insulin. A 14‐day masked baseline phase was followed by an 11‐week treatment phase during which participants used the device to monitor glucose levels. The primary end‐point was time spent in hypoglycemia (, Use of flash glucose monitoring technology in Japanese subjects with type 2 diabetes, treated with multiple daily insulin injections, resulted in increased time in range and decreased time in hyperglycemia without increasing hypoglycemia.

Aims/Introduction Glucose fluctuation (GF) is a residual risk factor for coronary artery disease (CAD). We investigated whether GF influenced clinical outcomes and progression of coronary stenosis in stable CAD patients. Materials and Methods In this prospective study, 101 consecutive lipid‐controlled stable CAD patients underwent percutaneous coronary intervention were enrolled, and GF was expressed as the mean amplitude of glycemic excursion (MAGE) obtained by continuous glucose monitoring before the procedure was evaluated. At 9 months after enrollment, culprit and non‐culprit (mild‐to‐moderate stenosis without ischemia) lesions were serially assessed by angiography. Cardiovascular events (CVE) consisting of cardiovascular death, non‐fatal myocardial infarction or ischemia‐driven revascularization during 2‐year follow up, rapid progression in non‐culprit lesions (defined as ≥10% luminal narrowing progression in lesions with stenosis ≥50%, ≥30% luminal narrowing progression in non‐culprit lesions with stenosis, Mean amplitude glucose excursion (MAGE) was significantly higher in patients with CVE than in those without CVE. The cut‐off value for the prediction of CVE by MAGE was 70.7 mg/dL. Higher MAGE was significantly associated with a high overall rate of CVE as well as of each component.

Aim To investigate the relationships between various clinical variables and the metformin-induced accumulation of fluorodeoxyglucose (FDG) in the intestine, with distinction between the intestinal wall and lumen, in individuals with type 2 diabetes who were receiving metformin treatment and underwent 18 F-labelled FDG ([18 F]FDG) positron emission tomography (PET)-MRI. Materials and methods We evaluated intestinal accumulation of [18 F]FDG with both subjective (a five-point visual scale determined by two experienced radiologists) and objective analyses (measurement of the maximum standardized uptake value [SUVmax ]) in 26 individuals with type 2 diabetes who were receiving metformin and underwent [18 F]FDG PET-MRI. [18 F]FDG accumulation within the intestinal wall was discriminated from that in the lumen on the basis of SUVmax . Results SUVmax for the large intestine was correlated with blood glucose level (BG) and metformin dose, but not with age, body mass index, HbA1c level or estimated glomerular filtration rate (eGFR). SUVmax for the small intestine was not correlated with any of these variables. Visual scale analysis yielded essentially similar results. Metformin dose and eGFR were correlated with SUVmax for the wall and lumen of the large intestine, whereas BG was correlated with that for the wall. Multivariable analysis identified metformin dose as an explanatory factor for SUVmax in the wall and lumen of the large intestine after adjustment for potential confounders including BG and eGFR. Conclusions Metformin dose is an independent determinant of [18 F]FDG accumulation in the wall and lumen of the large intestine in individuals treated with this drug.

Aims Information on the relative effects of insulin degludec (IDeg) and insulin glargine U300 (IGlarU300) on glycemic stability is limited and inconsistent. We directly compared the effects of these insulins on glycemic stability. Materials and methods In this multicenter, crossover trial, 46 individuals with type 1 diabetes and essentially undetectable circulating C-peptide were randomly assigned to the IDeg-first/IGlarU300-second or the IGlarU300-first/IDeg-second groups, and were treated with the respective basal insulins for 4-week periods. Data were collected in the last week of each treatment period. The primary aim was to examine the potential noninferiority of IDeg relative to IGlarU300 with regard to day-to-day variability, as evaluated by the standard deviation (SD), of fasting blood glucose (FBG) levels. Intraday glycemic variability and other parameters were also determined by continuous glucose monitoring (CGM). Results The SD of FBG for IDeg was noninferior to that for IGlarU300. The mean of FBG, coefficient of variation (CV) of FBG, and various glycemic variability indexes determined by CGM did not differ between the two insulins. Whereas the administered doses of the insulins also did not differ, the mean glycemic value was lower for IDeg than IGlarU300; the time above the target range (>180 mg/dL [10.0 mmol/L]) and the time below the target range ( Conclusions Our data suggest that IDeg and IGlarU300 have comparable glucose-stabilizing effects in individuals with type 1 diabetes. However, the glucose-lowering effect of IDeg may be greater than that of IGlarU300 when titrated with a unit-based protocol. CLINICAL TRIAL REGISTRY NUMBER: jRCTs051180138 (Japan Registry of Clinical Trials). This article is protected by copyright. All rights reserved.

Laparoscopic sleeve gastrectomy (LSG) is an important therapeutic option for morbidly obese patients. Although LSG promotes sufficient weight loss, how LSG changes plasma metabolites remains unclear. We assessed changes in plasma metabolite levels after LSG. We collected plasma samples from 15 morbidly obese Japanese patients before and 3 months after LSG. A total of 48 metabolites were quantified using capillary electrophoresis time‐of‐flight mass spectrometry‐based metabolomic profiling. Branched chain amino acids, several essential amino acids, choline, 2‐hydroxybutyric acid, 2‐oxoisovaleric acid and hypoxanthine were significantly decreased after LSG. Tricarboxylic acid cycle metabolites, including citric acid, succinic acid and malic acid, were significantly elevated after LSG. This is the first report to show dynamic alterations in plasma metabolite concentrations, as assessed using capillary electrophoresis time‐of‐flight mass spectrometry, in morbidly obese patients after LSG. Our results might show how LSG helps improve obesity, in part through metabolic status changes, and propose novel therapeutic targets to ameliorate obesity., Dynamic alterations in plasma metabolite concentrations in morbidly obese patients after laparoscopic sleeve gastrectomy.

Aims/Introduction Metformin therapy has been associated with vitamin B12 (VB12) deficiency, but information regarding this adverse effect in Asian populations is limited. We have now examined the relationship between metformin use and VB12 status in individuals with type 2 diabetes mellitus in Japan. Materials and Methods This cross‐sectional study was carried out with type 2 diabetes mellitus patients treated (Met group, n = 122) or not treated (control group, n = 63) with metformin. The primary end‐point was the difference in the serum concentration of homocysteine, a marker of VB12 activity, between the two groups. The serum concentrations of VB12, blood hemoglobin level and mean corpuscular volume were also compared between the groups. Subset analysis was carried out with individuals aged ≥70 years. The potential correlation between the daily dose or duration of metformin treatment and the other measured parameters was also examined. Results The level of homocysteine, as well as the VB12 level, hemoglobin concentration and mean corpuscular volume, did not differ significantly between the control and treated with metformin groups. The level of homocysteine was positively and that of VB12 negatively correlated with the daily dose of metformin. Among elderly individuals, the hemoglobin level was significantly lower in the treated with metformin group than in the control group, although the mean corpuscular volume was similar in the two groups. Conclusions The risk of VB12 deficiency during metformin treatment appears to be low in Japanese type 2 diabetes mellitus patients. However, high doses of metformin might result in a moderate decrease in the circulating VB12 level, as well as in anemia in elderly individuals., The risk of vitamin B12 deficiency during metformin treatment appears to be low in Japanese type 2 diabetes mellitus patients. However, high doses of metformin might result in a moderate decrease in the circulating vitamin B12 level, as well as in anemia in elderly individuals.

Aims/Introduction Sulfonylurea‐related hypoglycemia increases the risk of cardiovascular sequela, such as cardiac arrhythmia. This study aimed to clarify the relationship between the level of glycated hemoglobin (HbA1c) and the duration of hypoglycemia in type 2 diabetes patients treated with sulfonylureas. Materials and Methods Glucose levels in the enrolled patients (n = 300) were investigated with a professional continuous glucose monitoring device in the outpatient setting at six diabetes centers in Japan. Results A total of 269 participants completed the study. The duration of hypoglycemia with glucose values of 10% of the time in daily life (6.8 ± 5.6 min/h). The duration of hypoglycemia with glucose values of, The mean 24‐h glucose profiles over 24 h according to glycated hemoglobin level. The nadir of glucose levels was apparent between 03.00 and 05.00 hours irrespective of glycated hemoglobin level.

Aims/Introduction Insulin resistance syndrome (IRS) of type A or B is triggered by gene abnormalities of or autoantibodies to the insulin receptor, respectively. Rabson–Mendenhall/Donohue syndrome is also caused by defects of the insulin receptor gene (INSR), but is more serious than type A IRS. Here, we carried out a nationwide survey of these syndromes in Japan. Materials and Methods We sent questionnaires to a total of 1,957 academic councilors or responsible individuals at certified facilities of the Japan Diabetes Society, as well as at the department pediatrics or neonatology in medical centers with >300 beds. Results We received 904 responses with information on 23, 30 and 10 cases of type A or B IRS and Rabson–Mendenhall/Donohue syndrome, respectively. Eight cases with type A IRS‐like clinical features, but without an abnormality of INSR, were tentatively designated type X IRS, with five of these cases testing positive for PIK3R1 mutations. Fasting serum insulin levels at diagnosis (mean ± standard deviation) were 132.0 ± 112.4, 1122.1 ± 3292.5, 2895.5 ± 3181.5 and 145.0 ± 141.4 μU/mL for type A IRS, type B IRS, Rabson–Mendenhall/Donohue syndrome and type X IRS, respectively. Type A and type X IRS, as well as Rabson–Mendenhall/Donohue syndrome were associated with low birthweight. Type B IRS was diagnosed most frequently in older individuals, and was often associated with concurrent autoimmune conditions and hypoglycemia. Conclusions Information yielded by this first nationwide survey should provide epidemiological insight into these rare conditions and inform better healthcare for affected patients., (a) Rabson–Mendenhall/Donohue syndrome and type B insulin resistance syndrome (IRS) showed the highest and second highest levels of hyperinsulinemia, respectively, and those with type A and type X IRS were similar. Fasting serum insulin levels for 26 of the 27 (96.3%) type A and type X IRS patients for whom such data were available were >30 μU/mL. (b) Type A and type X IRS, as well as Rabson–Mendenhall/Donohue syndrome were associated with low birthweight.

Aims/Introduction Fat‐specific protein 27 (FSP27) α is the major isoform of FSP27 in white adipose tissue (WAT), and is essential for large unilocular lipid droplet (LD) formation in white adipocytes. In contrast, FSP27β is abundantly expressed in brown adipose tissue (BAT), and plays an important role in small multilocular LD formation. In FSP27 KO mice in which FSP27α and β are both depleted, WAT is characterized by multilocular LD formation, and by increased mitochondrial abundance and energy expenditure, whereas BAT conversely manifests large oligolocular LDs and reduced energy expenditure. Materials and Methods We investigated the effects of autophagy in WAT and BAT of wild type (WT) and FSP27 knockout (KO) mice. In addition, we examined the effects of FSP27α and FSP27β to the induction of autophagy in COS cells. Results Food deprivation induced autophagy in BAT of WT mice, as well as in WAT of FSP27 KO mice, suggesting that enhanced autophagy is characteristic of adipocytes with small multilocular LDs. Pharmacological inhibition of autophagy attenuated the fasting‐induced loss of LD area in adipocytes with small multilocular LDs (BAT of WT mice and WAT of FSP27 KO mice), without affecting that in adipocytes with large unilocular or oligolocular LDs (WAT of WT mice or in BAT of FSP27 KO mice). Overexpression of FSP27α inhibited autophagy induction by serum deprivation in COS cells, whereas that of FSP27β had no such effect. Conclusions The present results thus showed that FSP27α inhibits autophagy and might thereby contribute to the energy‐storage function of WAT.

Administration of an sodium-glucose cotransporter 2 inhibitor to individuals with insulin resistance reduces the level of glucose disposal necessary to maintain glycemia as a result of the induced increase in urinary glucose excretion. The amount of insulin required for a certain level of glucose disposal, on which the evaluation of insulin resistance is usually based, might thus decrease even without amelioration of insulin resistance.

Aims/Introduction The preservation of pancreatic β‐cell mass is an essential factor in the onset and development of type 2 diabetes mellitus. Recently, sodium–glucose cotransporter 2 inhibitors have been launched as antihyperglycemic agents, and their organ‐protective effects are attracting attention. They are also reported to have favorable effects on the preservation of pancreatic β‐cell mass, but the appropriate timing for the administration of sodium–glucose cotransporter 2 inhibitors is obscure. Materials and Methods In the present study, we administered a sodium–glucose cotransporter 2 inhibitor, dapagliflozin, to an animal model of type 2 diabetes mellitus, db/db mice, and investigated the adequate timing and duration for its administration. We also carried out microarray analysis using pancreatic islets from db/db mice. Results We found that dapagliflozin preserved pancreatic β‐cell mass depending on the duration of administration and markedly improved blood glucose levels. If the duration was the same, the earlier administration of dapagliflozin was more effective in preserving pancreatic β‐cell mass, increasing serum insulin levels and improving blood glucose levels. From microarray analysis, we discovered that the expression of Agr2, Tff2 and Gkn3 was significantly upregulated after the early administration of dapagliflozin. This upregulated gene expression might provide a legacy effect for the preservation of pancreatic β‐cell mass. Conclusions We expect that the early administration of dapagliflozin would provide a long‐lasting effect in preserving pancreatic β‐cell mass.

Aims/Introduction Sodium–glucose cotransporter 2 (SGLT‐2) inhibitors improve blood glucose control, as well as reducing bodyweight by promoting urinary glucose excretion. The weight loss is less than expected from urinary glucose loss, however, likely because of an increase in food intake. To investigate whether SGLT‐2 inhibitors might increase appetite by affecting related hormones, we examined the effects of the SGLT‐2 inhibitor, ipragliflozin, including those on appetite‐regulating hormones, in individuals with suboptimally controlled type 2 diabetes. Materials and Methods The present prospective, multicenter, open‐label study was carried out with 96 patients with a body mass index of ≥22 kg/m2 who were treated with ipragliflozin (50 mg/day) for 16 weeks. Parameters including glycated hemoglobin level, bodyweight, circulating leptin and active ghrelin concentrations, and appetite as assessed with a visual analog scale were measured before and during treatment. Results Both glycated hemoglobin level (from 7.9 ± 0.8 to 7.1 ± 0.7%) and bodyweight (from 75.2 ± 12.6 to 72.6 ± 12.4 kg) were significantly decreased after treatment for 16 weeks. The fasting serum leptin level was significantly decreased after 2 weeks (from 19.5 ± 13.1 to 18.1 ± 12.4 ng/mL) and remained decreased up to 16 weeks, even after adjustment for bodyweight, whereas the plasma active ghrelin level showed no significant change. The visual analog scale score for hunger was significantly increased at 2 and 8 weeks. Conclusions The present results suggest that ipragliflozin improved glycemic control and reduced bodyweight, but also reduced serum leptin levels and might thereby have increased appetite.

A Japanese woman aged in her late 30s with severe insulin resistance and bodily features including a triangular face, prominent forehead, small chin, large and low‐set ears, and ocular depression was investigated. A similar phenotype was not observed in other family members with the exception of her son, suggesting that the condition was caused by a de novo mutation that was transmitted from mother to son. Exome analysis showed the presence in the proband and her son of a c.1945C>T mutation in PIK3R1, a common mutation associated with SHORT (short stature, hyperextensibility of joints and/or inguinal hernia, ocular depression, Rieger anomaly, and teething delay) syndrome. Administration of a sodium–glucose cotransporter 2 inhibitor lowered the proband's hemoglobin A1c level and allowed a reduction in her insulin dose without treatment‐related adverse events including ketoacidosis, exaggerated loss of body mass or hypoglycemia. Sodium–glucose cotransporter 2 inhibitors might thus offer an additional option for the treatment of genetic syndromes of severe insulin resistance.

Aims/introduction Whereas some clinical studies have shown that excessive fat accumulation in the pancreas is associated with impairment of insulin secretion, others have not found such an association. 1 H magnetic resonance spectroscopy allows quantitative fat analysis in various tissues including the pancreas. The pathological relevance of pancreatic fat content (PFC) in Japanese individuals remains unclear, however. Materials and methods We analyzed PFC in 30 Japanese individuals with normal glucose tolerance by 1 H magnetic resonance spectroscopy, and then investigated the relationships between PFC and indexes of insulin secretion and insulin sensitivity-resistance determined by an oral glucose tolerance test. We also measured hepatic fat content and intramyocellular lipid content by 1 H magnetic resonance spectroscopy, as well as visceral fat area and subcutaneous fat area by magnetic resonance imaging, and we examined the relationships between these fat content measures and oral glucose tolerance test-derived parameters. Results PFC was correlated with indexes of insulin sensitivity-resistance, but not with those of insulin secretion. Hepatic fat content and visceral fat area were correlated with similar sets of parameters as was PFC, whereas subcutaneous fat area was correlated with parameters of insulin secretion, and intramyocellular lipid content was not correlated with any of the measured parameters. The correlation between PFC and homeostasis model assessment of insulin resistance remained significant after adjustment for age, body mass index and sex. Among fat content measures, PFC was most highly correlated with hepatic fat content and visceral fat area. Conclusions PFC was correlated with indexes of insulin resistance, but not with those of insulin secretion in non-obese Japanese individuals with normal glucose tolerance.

Aims/Introduction Increased glycemic variability is an important contributing factor to coronary artery disease. Although various parameters of glycemic variability can be derived by continuous glucose monitoring, the clinical relevance of individual parameters has remained unclear. We have now analyzed the relationship of such parameters to coronary plaque vulnerability. Materials and Methods The standard deviation of glucose levels (SD glucose), mean amplitude of glycemic excursions (MAGE), continuous overlapping net glycemic action calculated every 1 h (CONGA‐1) and mean of daily differences (MODD) were calculated from continuous glucose monitoring data for 53 patients hospitalized for percutaneous coronary intervention. The relationship of these parameters to the percentage necrotic core of total plaque volume (%NC) as assessed by virtual histology–intravascular ultrasound (a predictor of coronary plaque rupture) was evaluated. Results All parameters of glycemic variability were significantly correlated with %NC, with correlation coefficients of 0.593, 0.626, 0.318, and 0.388 for log(SD glucose), log(MAGE), CONGA‐1 and log(MODD), respectively. Simple linear regression analysis showed that the coefficients of determination for %NC and either log(SD glucose; 0.352) or log(MAGE; 0.392) were greater than those for %NC and either CONGA‐1 (0.101) or log(MODD; 0.151), whereas the residual sums of squares for the former relationships (1045.1 and 979.5, respectively) were smaller than those for the latter (1449.3 and 1369.6, respectively). Conclusions The present data suggest that SD glucose and MAGE are more highly correlated with coronary plaque vulnerability than are CONGA‐1 and MODD, and are thus likely better predictors of coronary artery disease.

Recent evidence suggests that metformin exerts glucose‐lowering effects via its action in the gut. The accumulation in the colon of (18)F‐labeled fluorodeoxyglucose (FDG), a nonmetabolizable derivative of glucose, is markedly augmented after metformin administration, indicating that metformin affects the handling of glucose in colon whereas the underlying mechanism and the significance to glucose metabolism of the finding remain to be determined.

We evaluated age-dependent changes in β-cell function as assessed with an oral glucose tolerance test (OGTT)-based analog of the disposition index (oral disposition index). A total of 110 Japanese normoglycemic subjects (aged 22-59 years) was divided into decadal age groups (20, 30, 40 and 50 s) and subjected to an OGTT. The oral disposition index was calculated as the product of the Matsuda index and the ratio of the area under the insulin curve to the area under the glucose curve for 0-120 min during the OGTT (AUCins/gluc120). Although indexes of insulin secretion, including AUCins/gluc120 and the insulinogenic index, did not differ among age groups, the oral disposition index differed significantly among decadal ages and declined with age. The oral disposition index is thus a sensitive measure of β-cell function, and a natural decline in such function likely begins in early adulthood and progresses with age. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00099.x, 2011).