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Oral antidiabetic drugs (OADs) are used for more than a half-century in the treatment of type 2 diabetes. Only in the last five years, intensive research has been conducted in the pharmacogenetics of these drugs based mainly on the retrospective register studies, but only a handful of associations detected in these studies were replicated. The gene variants in CYP2C9, ABCC8/KCNJ11, and TCF7L2 were associated with the effect of sulfonylureas. CYP2C9 encodes sulfonylurea metabolizing cytochrome P450 isoenzyme 2C9, ABCC8 and KCNJ11 genes encode proteins constituting ATP-sensitive K(+) channel which is a therapeutic target for sulfonylureas, and TCF7L2 is a gene with the strongest association with type 2 diabetes. SLC22A1, SLC47A1, and ATM gene variants were repeatedly associated with the response to metformin. SLC22A1 and SLC47A1 encode metformin transporters OCT1 and MATE1, respectively. The function of a gene variant near ATM gene identified by a genome-wide association study is not elucidated so far. The first variant associated with the response to gliptins is a polymorphism in the proximity of CTRB1/2 gene which encodes chymotrypsinogen. Establishment of diabetes pharmacogenetics consortia and reduction in costs of genomics might lead to some significant clinical breakthroughs in this field in a near future.

Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood. Previous genome-wide association studies of birth weight identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes and a second variant, near CCNL1, with no obvious link to adult traits. In an expanded genome-wide association meta-analysis and follow-up study of birth weight (of up to 69,308 individuals of European descent from 43 studies), we have now extended the number of loci associated at genome-wide significance to 7, accounting for a similar proportion of variance as maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes, ADRB1 with adult blood pressure and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism.

Aims: To systematically review the evidence for the effect of vitamin D supplementation on glycaemia, insulin resistance, progression to diabetes and complications of diabetes., Methods: Systematic review and meta-analysis. We searched databases including MEDLINE, EMBASE and the Cochrane Library for randomized controlled trials comparing vitamin D or analogues with placebo. We extracted data on fasting glucose, glycaemic control, insulin resistance, insulin/C-peptide levels, micro- and macrovascular outcomes and progression from non-diabetes to diabetes. Studies were assessed independently by two reviewers according to a pre-specified protocol., Results: Fifteen trials were included in the systematic review. Trial reporting was of moderate, variable quality. Combining all studies, no significant improvement was seen in fasting glucose, HbA(1c) or insulin resistance in those treated with vitamin D compared with placebo. For patients with diabetes or impaired glucose tolerance, meta-analysis showed a small effect on fasting glucose (-0.32 mmol/l, 95%CI -0.57 to -0.07) and a small improvement in insulin resistance (standard mean difference -0.25, 95%CI -0.48 to -0.03). No effect was seen on glycated haemoglobin in patients with diabetes and no differences were seen for any outcome in patients with normal fasting glucose. Insufficient data were available to draw conclusions regarding micro- or macrovascular events; two trials failed to show a reduction in new cases of diabetes in patients treated with vitamin D., Conclusions: There is currently insufficient evidence of beneficial effect to recommend vitamin D supplementation as a means of improving glycaemia or insulin resistance in patients with diabetes, normal fasting glucose or impaired glucose tolerance., (© 2012 The Authors. Diabetic Medicine © 2012 Diabetes UK.)

Aims/hypothesis: In this study we aimed to replicate the previously reported association between the glycaemic response to metformin and the SNP rs11212617 at a locus that includes the ataxia telangiectasia mutated (ATM) gene in multiple additional populations., Methods: Incident users of metformin selected from the Diabetes Care System West-Friesland (DCS, n = 929) and the Rotterdam Study (n = 182) from the Netherlands, and the CARDS Trial (n = 254) from the UK were genotyped for rs11212617 and tested for an association with both HbA(1c) reduction and treatment success, defined as the ability to reach the treatment target of an HbA(1c) ≤ 7 % (53 mmol/mol). Finally, a meta-analysis including data from literature was performed., Results: In the DCS cohort, we observed an association between rs11212617 genotype and treatment success on metformin (OR 1.27, 95% CI 1.03, 1.58, p = 0.028); in the smaller Rotterdam Study cohort, a numerically similar but non-significant trend was observed (OR 1.45, 95% CI 0.87, 2.39, p = 0.15); while in the CARDS cohort there was no significant association. In meta-analyses of these three cohorts separately or combined with the previously published cohorts, rs11212617 genotype is associated with metformin treatment success (OR 1.24, 95% CI 1.04, 1.49, p = 0.016 and OR 1.25, 95% CI 1.33, 1.38, p = 7.8 × 10(-6), respectively)., Conclusions/interpretation: A gene variant near ATM is significantly associated with metformin treatment response in type 2 diabetic patients from the Netherlands and the UK. This is the first robustly replicated common susceptibility locus found to be associated with metformin treatment response.

Introduction: The young-onset diabetes seen in HNF1A-MODY is often misdiagnosed as Type 2 diabetes. Type 2 diabetes, unlike HNF1A-MODY, is associated with insulin resistance and a characteristic dyslipidaemia. We aimed to compare the lipid profiles in HNF1A-MODY, Type 2 diabetes and control subjects and to determine if lipids can be used to aid the differential diagnosis of diabetes sub-type., Methods: 1) 14 subjects in each group (HNF1A-MODY, Type 2 diabetes and controls) were matched for gender and BMI. Fasting lipid profiles and HDL lipid constituents were compared in the 3 groups. 2) HDL-cholesterol was assessed in a further 267 patients with HNF1A-MODY and 297 patients with a diagnosis of Type 2 diabetes to determine its discriminative value., Results: 1) In HNF1A-MODY subjects, plasma-triglycerides were lower (1.36 vs. 1.93 mmol/l, p = 0.07) and plasma-HDL-cholesterol was higher than in subjects with Type 2 diabetes (1.47 vs. 1.15 mmol/l, p = 0.0008), but was similar to controls. Furthermore, in the isolated HDL; HDL-phospholipid and HDL-cholesterol ester content were higher in HNF1A-MODY, than in Type 2 diabetes (1.59 vs. 1.33 mmol/L, p = 0.04 and 1.10 vs. 0.83 mmol/L, p = 0.019, respectively), but were similar to controls (1.59 vs. 1.45 mmol/L, p = 0.35 and 1.10 vs. 1.21 mmol/L, p = 0.19, respectively). 2) A plasma-HDL-cholesterol > 1.12 mmol/L was 75% sensitive and 64% specific (ROC AUC = 0.76) at discriminating HNF1A-MODY from Type 2 diabetes., Conclusion: The plasma-lipid profiles of HNF1A-MODY and the lipid constituents of HDL are similar to non-diabetic controls. However, HDL-cholesterol was higher in HNF1A-MODY than in Type 2 diabetes and could be used as a biomarker to aid in the identification of patients with HNF1A-MODY., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Obesity is highly associated with elevated serum triglycerides, hepatic steatosis and type 2 diabetes (T2D). The I148M (rs738409) genetic variant of patatin-like phospholipase domain-containing 3 gene (PNPLA3) is known to modulate hepatic triglyceride accumulation, leading to steatosis. No association between PNPLA3 I148M genotype and T2D in Europeans has been reported. Aim of this study is to examine the relationship between PNPLA3 I148M genotypes and serum triglycerides, insulin resistance and T2D susceptibility by testing a gene-environment interaction model with severe obesity., Methods and Findings: PNPLA3 I148M was genotyped in a large obese cohort, the SOS study (n = 3,473) and in the Go-DARTS (n = 15,448), a T2D case-control study. Metabolic parameters were examined across the PNPLA3 I148M genotypes in participants of the SOS study at baseline and at 2- and 10-year follow up after bariatric surgery or conventional therapy. The associations with metabolic parameters were validated in the Go-DARTS study. Serum triglycerides were found to be lower in the PNPLA3 148M carriers from the SOS study at baseline and from the Go-DARTS T2D cohort. An increased risk for T2D conferred by the 148M allele was found in the SOS study (O.R. 1.09, 95% C.I. 1.01-1.39, P = 0.040) and in severely obese individuals in the Go-DARTS study (O.R. 1.37, 95% C.I. 1.13-1.66, P = 0.001). The 148M allele was no longer associated with insulin resistance or T2D after bariatric surgery in the SOS study and no association with the 148M allele was observed in the less obese (BMI<35) individuals in the Go-DARTS study (P for interaction  = 0.002). This provides evidence for the obesity interaction with I48M allele and T2D risk in a large-scale cross-sectional and a prospective interventional study., Conclusions: Severely obese individuals carrying the PNPLA3 148M allele have lower serum triglyceride levels, are more insulin resistant and more susceptible to T2D. This study supports the hypothesis that obesity-driven hepatic lipid accumulation may contribute to T2D susceptibility.

The rapid rise in prevalence of type 2 diabetes mellitus (T2DM) has been driven by changes in environmental factors - primarily increased caloric intake and reduced energy expenditure - resulting in reduced whole body insulin sensitivity (often termed insulin resistance). Insulin resistance has been proposed to be a major driver of progression to T2DM. However, of 38 individual susceptibility loci for T2DM recently identified by genome wide association studies, by far the majority code for proteins involved in β-cell function. In this review, we discuss the possible reasons for the paucity of insulin resistance genes and ask whether the new genetic susceptibility data should focus attention on β-cell targets in the development of therapies for T2DM., (Copyright © 2010 Elsevier Inc. All rights reserved.)

SLCO1B1 gene variants are associated with severe statin-induced myopathy. We examined whether these variants are also associated with general statin intolerance in a large population of patients with type 2 diabetes receiving statins as part of routine clinical care. A total of 4,196 individuals were genotyped for rs4149056 (Val174Ala) and rs2306283 (Asp130Asn). Intolerance was defined by serum biochemistry and also by discontinuation, switching, or reduction in dose of the prescribed statin drug. Ala174 was associated with higher intolerance (odds ratio = 2.05, P = 0.043), whereas Asp130 was associated with lower intolerance (odds ratio = 0.71, P = 0.026). Ala174 was associated with a lower low-density lipoprotein cholesterol (LDLc) response to statins (P = 0.01) whereas 130D was associated with a greater LDLc response to statins (P = 0.048), as previously reported; however, this association was no longer present when data for statin-intolerant individuals were removed from the analysis. This study suggests that common genetic variants selected for an extreme phenotype of statin-induced myopathy also predispose to more common milder statin intolerance and may, for this reason, impact lipid-lowering efficacy.

Metformin is the most commonly used pharmacological therapy for type 2 diabetes. We report a genome-wide association study for glycemic response to metformin in 1,024 Scottish individuals with type 2 diabetes with replication in two cohorts including 1,783 Scottish individuals and 1,113 individuals from the UK Prospective Diabetes Study. In a combined meta-analysis, we identified a SNP, rs11212617, associated with treatment success (n = 3,920, P = 2.9 × 10(-9), odds ratio = 1.35, 95% CI 1.22-1.49) at a locus containing ATM, the ataxia telangiectasia mutated gene. In a rat hepatoma cell line, inhibition of ATM with KU-55933 attenuated the phosphorylation and activation of AMP-activated protein kinase in response to metformin. We conclude that ATM, a gene known to be involved in DNA repair and cell cycle control, plays a role in the effect of metformin upstream of AMP-activated protein kinase, and variation in this gene alters glycemic response to metformin.

Background: Primary hyperparathyroidism (PHPT) is associated with insulin resistance and an increased cardiovascular mortality. We aimed to see if parathyroidectomy improved insulin resistance., Methods: Twelve PHPT patients undergoing parathyroidectomy and ten control patients undergoing non-neck surgery were recruited to the study. Fasting venous blood samples were collected immediately pre-operatively and again at five to six weeks post-operatively. Samples were assayed for plasma glucose, serum insulin, total cholesterol, triglycerides, calcium, alkaline phosphatase, magnesium, parathyroid hormone (PTH), and haemoglobin A1c (HbA1c). Insulin resistance was calculated from fasting insulin and glucose values using Homeostasis Model Assessment (HOMA)., Results: Parathyroidectomy decreased serum calcium (mean pre-op = 2.85 mmol/L, post-op 2.28 mmol/L, P < 0.001) and PTH concentrations (mean pre-op = 23.33 pmol/L, post-op = 10.23 pmol/L, P < 0.001) and increased phosphate concentration. However, there was no improvement in insulin resistance in the PHPT group at between 5 and 6 weeks post-operatively (geometric mean; pre-op = 0.88 (95% CI 0.59 - 1.33) vs. post-op = 0.88 (0.66 - 1.17) P = 0.95). In the control group, an increase in serum calcium was observed post-operatively (mean pre-op = 2.29 mmol/L, post-op = 2.35 mmol/L, P = 0.03). No change in insulin resistance was observed (geometric mean; pre-op = 1.37 (95% CI 0.89 - 2.11) vs. post-op = 1.38 (0.72 - 2.67) P = 0.96)., Conclusion: In summary, no significant change in insulin resistance post-parathyroidectomy in patients with PHPT was observed. This indicates that surgical treatment of PHPT does not improve insulin resistance for patients currently selected for parathyroidectomy.

Aims: To investigate all-cause and cardiovascular mortality in subjects with diabetes caused by a mutation in the hepatocyte nuclear factor 1alpha gene (HNF1A)., Methods: We identified 39 British families with HNF1A mutations. Consenting individuals were asked details of age and cause of death of parents and siblings. Copies of death certificates were requested from the family or were obtained via the Offices for National Statistics., Results: Data were collated on 241 control subjects and 153 mutation carriers. Of those who died, 66% of mutation carriers died from a cardiovascular-related illness compared with 43% of control subjects (P = 0.02). Family members with HNF1A mutations died at a younger age than familial control subjects [all-cause hazard ratio, adjusting for sex and smoking status: 1.9 (95% confidence interval 1.2, 2.9, P = 0.006; cardiovascular hazard ratio: 2.3, confidence interval 1.3, 4.2, P = 0.006)]., Conclusions: We have shown that individuals known to have diabetes caused by a mutation in the HNF1A gene have an increased risk of cardiovascular mortality compared with their unaffected family members. As with other forms of diabetes, consideration should be given to early statin therapy despite a seemingly protective lipid profile.

Objective: Metformin is actively transported into the liver by the organic cation transporter (OCT)1 (encoded by SLC22A1). In 12 normoglycemic individuals, reduced-function variants in SLC22A1 were shown to decrease the ability of metformin to reduce glucose excursion in response to oral glucose. We assessed the effect of two common loss-of-function polymorphisms in SLC22A1 on metformin response in a large cohort of patients with type 2 diabetes., Research Design and Methods: The Diabetes Audit and Research in Tayside Scotland (DARTS) database includes prescribing and biochemistry information and clinical phenotypes of all patients with diabetes within Tayside, Scotland, from 1992 onwards. R61C and 420del variants of SLC22A1 were genotyped in 3,450 patients with type 2 diabetes who were incident users of metformin. We assessed metformin response by modeling the maximum A1C reduction in 18 months after starting metformin and investigated whether a treatment target of A1C <7% was achieved. Sustained metformin effect on A1C between 6 and 42 months was also assessed, as was the time to metformin monotherapy failure. Covariates were SLC22A1 genotype, BMI, average drug dose, adherence, and creatinine clearance., Results: A total of 1,531 patients were identified with a definable metformin response. R61C and 420del variants did not affect the initial A1C reduction (P = 0.47 and P = 0.92, respectively), the chance of achieving a treatment target (P = 0.83 and P = 0.36), the average A1C on monotherapy up to 42 months (P = 0.44 and P = 0.75), or the hazard of monotherapy failure (P = 0.85 and P = 0.56)., Conclusions: The SLC22A1 loss-of-function variants, R61C and 420del, do not attenuate the A1C reduction achieved by metformin in patients with type 2 diabetes.

Aim: Metformin is the most commonly prescribed oral agent used in the treatment of type 2 diabetes. It is effective at reducing glycosylated Haemoglobin (HbA1c) and decreasing microvascular and macrovascular disease. However, up to 25% of patients develop gastrointestinal side effects leading to cessation in 5-10% of users. Metformin XL (glucophage SR) is a once a day preparation that delays absorption, leading to decreased peak metformin concentrations. We hypothesised that the XL preparation of metformin would be better tolerated than the standard immediate release (IR) preparation leading to improved adherence to therapy., Methods: In a retrospective observational study, we studied adherence and glycaemic control in patients prescribed metformin IR and XL preparations in Tayside, UK., Results: Metformin XL was used by 137 patients during the study period. Overall adherence was greater in the XL group (80%) compared with the 10,772 patients in the IR group (72%, p = 0.0026). In the 40 patients who changed from metformin IR to metformin XL who had sufficient data to determine adherence, the adherence increased from 62% in the IR group to 81% in the XL group (p < 0.0001). This was associated with an HbA1c reduction from 9.1 to 8.4% (p = 0.0739, n = 29)., Conclusions: Metformin XL use is associated with increased adherence compared with the IR preparation, although the mechanism for this cannot be determined from this study. In patients intolerant of metformin IR the XL preparation should be considered.

Genetic variation can impact on efficacy and risk of adverse events to commonly used oral agents in -diabetes. Metformin is not metabolized and its mechanism of action remains debated; however, several cation transporters have been identified. Variation in these pharmacokinetic genes might influence metformin response. Conversely, although the cytochrome P450 system has been implicated in sulfonylurea response in some small studies, to date variants affecting pharmacodynamics, including those in ABCC8 (SUR1) and TCF7L2, are the most promising. For thiazolidinedione response, variants in PPARG or ADIPOQ (adiponectin) have been variably associated with response. With increasing well-phenotyped cohorts and new methods, including genome-wide association studies, the next few years offer great hope to use pharmacogenetics to unravel drug and disease mechanisms, as well as the possibility to individualize therapy by genotype.

Background: Mutations in the KCNJ11 gene encoding the adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP)) subunit Kir6.2 are the most frequent cause of diabetes in infancy. Sulfonylurea (SU) treatment restores insulin secretion in patients with KCNJ11 mutations., Materials and Methods: We report a 9-year-old boy who presented at the age of three months with diabetic ketoacidosis. Results Sequencing of the KCNJ11 gene revealed an R201H mutation. Therefore, he was transferred from insulin to oral SU therapy. He required a high-threshold dose before insulin could be discontinued. After transition, a subsequent dose reduction was necessary to avoid hypoglycemia. Improved sustained metabolic control without complications was achieved on a low SU maintenance dose twice daily over 36 months., Conclusion: SU therapy is safe for patients with diabetes due to KCNJ11 mutations. The mechanism of a threshold dose and the twice-daily requirement needs further attention.

This review focuses on current evidence for pharmacogenetics for the 3 commonly used drug classes in treating diabetes: metformin, sulphonylureas and thiazolidinediones. Currently, metformin pharmacogenetics is focussing on drug transport with the recent finding that variation in OCT transporters might affect metformin response. An aetiological approach has identified monogenic patients with diabetes due to TCF1 mutations who are particularly sensitive to the hypoglycaemic effects of sulphonylureas, and KCNJ11 or ABCC8 mutations in which sulphonylureas can be used in place of insulin treatment. In Type 2 diabetes sulphonylurea response has been shown to be associated with variants TCF7L2 associated with type 2 diabetes risk. For thiazolidinediones, focus has been on PPARgamma variants although with no consistent result. Genome wide association studies offer great potential to unravel what genetic factors influence response and side effects of diabetes therapies. Large numbers of well phenotyped patients for response and side effect as well as similarly sized similarly phenotyped replication cohorts are required. Establishing such cohorts is a priority in diabetes pharmacogenetics research.

Heterozygous activating mutations of KCNJ11 (Kir6.2) are the most common cause of permanent neonatal diabetes mellitus (PNDM) and several cases have been successfully treated with oral sulfonylureas. We report on the attempted transfer of insulin therapy to glibenclamide in a 4-year old child with PNDM and DEND syndrome, bearing a C166Y mutation in KCNJ11. An inpatient transition from subcutaneous NPH insulin (0.2 units/kg/d) to oral glibenclamide (1 mg/kg/d and 1.5 mg/kg/d) was performed. Glucose and C-peptide responses stimulated by oral glucose tolerance test (OGTT), hemoglobin A1c levels, the 8-point self-measured blood glucose (SMBG) profile and the frequency of hypoglycemia episodes were analyzed, before and during treatment with glibenclamide. Neither diabetes control nor neurological improvements were observed. We concluded that C166Y mutation was associated with a form of PNDM insensitive to glibenclamide.

Activating mutations in the pore-forming Kir6.2 (KCNJ11) and regulatory sulphonylurea receptor SUR1 (ABCC8) subunits of the K(ATP) channel are a common cause of transient neonatal diabetes mellitus (TNDM). We identified a new TNDM mutation (R826W) in the first nucleotide-binding domain (NBD1) of SUR1. The mutation was found in a region that heterodimerizes with NBD2 to form catalytic site 2. Functional analysis showed that this mutation decreases MgATP hydrolysis by purified maltose-binding protein MBP-NBD1 fusion proteins. Inhibition of ATP hydrolysis by MgADP or BeF was not changed. The results indicate that the ATPase cycle lingers in the post-hydrolytic MgADP.P(i)-bound state, which is associated with channel activation. The extent of MgADP-dependent activation of K(ATP) channel activity was unaffected by the R826W mutation, but the time course of deactivation was slowed. Channel inhibition by MgATP was reduced, leading to an increase in resting whole-cell currents. In pancreatic beta cells, this would lead to less insulin secretion and thereby diabetes.

After many years of effort with only modest result, the last 5 years has seen a tremendous surge in our understanding of the genetics of diabetes. This review will focus on the therapeutic implications of diagnosing monogenic diabetes and the recent advances in type 1 and type 2 diabetes genetics following the development of Genome Wide Association studies.

Aims/hypothesis: The gene encoding transcription factor 7-like 2 (TCF7L2) has been identified as a type 2 diabetes locus from genome-wide linkage studies and subsequent association analysis. We investigated the role of two common variants in TCF7L2 in a large case-control study recruited from the Tayside region of Scotland, UK., Subjects and Methods: We genotyped 6,516 participants for rs12255372 and rs7903146 and analysed the role in type 2 diabetes susceptibility using binary logistic regression. Age, sex and obesity status were examined as covariates. The distribution of the genotypes within different treatment groups of cases was examined., Results: Both variants were associated with type 2 diabetes (p < 10(-13)). The variants were present at very similar frequencies and were in strong linkage disequilibrium (R(2) = 0.88, D' = 0.89). A gene dosage effect of the rare allele of both variants was observed, the heterozygote CT group of rs7903146 having an odds ratio of 1.36 (95% CI 1.2-1.5, p=1.54 x 10(-7)) for type 2 diabetes and the TT homozygote having a greater risk (OR = 2.03, 95% CI 1.7-2.5, p=1.40 x 10(-12)). An interaction with sex was observed, the males displaying a higher degree of genotype-associated risk compared with the females (p = 0.023). The T allele was associated with increased HbA(1c) levels in both cases and controls, and with decreased BMI and waist circumference in case but not controls. The T allele was overrepresented in individuals requiring insulin treatment and underrepresented in the patients being managed by diet alone (p = 0.006)., Conclusions: We have confirmed TCF7L2 to be a diabetes locus in a large case-control study in Tayside, UK. Our data suggest that variants of TCF7L2 may be associated with increased disease severity and therapeutic failure.

Background: Macrosomia is associated with considerable neonatal and maternal morbidity. Factors that predict macrosomia are poorly understood. The increased rate of macrosomia in the offspring of pregnant women with diabetes and in congenital hyperinsulinaemia is mediated by increased foetal insulin secretion. We assessed the in utero and neonatal role of two key regulators of pancreatic insulin secretion by studying birthweight and the incidence of neonatal hypoglycaemia in patients with heterozygous mutations in the maturity-onset diabetes of the young (MODY) genes HNF4A (encoding HNF-4alpha) and HNF1A/TCF1 (encoding HNF-1alpha), and the effect of pancreatic deletion of Hnf4a on foetal and neonatal insulin secretion in mice., Methods and Findings: We examined birthweight and hypoglycaemia in 108 patients from families with diabetes due to HNF4A mutations, and 134 patients from families with HNF1A mutations. Birthweight was increased by a median of 790 g in HNF4A-mutation carriers compared to non-mutation family members (p < 0.001); 56% (30/54) of HNF4A-mutation carriers were macrosomic compared with 13% (7/54) of non-mutation family members (p < 0.001). Transient hypoglycaemia was reported in 8/54 infants with heterozygous HNF4A mutations, but was reported in none of 54 non-mutation carriers (p = 0.003). There was documented hyperinsulinaemia in three cases. Birthweight and prevalence of neonatal hypoglycaemia were not increased in HNF1A-mutation carriers. Mice with pancreatic beta-cell deletion of Hnf4a had hyperinsulinaemia in utero and hyperinsulinaemic hypoglycaemia at birth., Conclusions: HNF4A mutations are associated with a considerable increase in birthweight and macrosomia, and are a novel cause of neonatal hypoglycaemia. This study establishes a key role for HNF4A in determining foetal birthweight, and uncovers an unanticipated feature of the natural history of HNF4A-deficient diabetes, with hyperinsulinaemia at birth evolving to decreased insulin secretion and diabetes later in life.

Aims/hypothesis: There is strong evidence that maternal diabetes while offspring are in utero results in offspring beta cell dysfunction and diabetes or glucose intolerance. Offspring born to mothers with a mutation in the glucokinase gene (GCK) are a good model for studying exposure to moderate hyperglycaemia, as mutation carriers have fasting hyperglycaemia throughout life including during pregnancy. We assessed the long term effects of exposure to maternal hyperglycaemia in utero on beta cell function and glucose tolerance in adult offspring., Materials and Methods: We studied 86 adult offspring (mean age 40 years), 49 born to glucokinase mothers (exposed to hyperglycaemia in utero) and 37 born to glucokinase fathers (controls). We measured glucose tolerance during an OGTT and beta cell function using early insulin response (EIR); we also measured anthropometric data including birthweight., Results: Offspring of glucokinase mothers had a higher birthweight by 450 g (p<0.001), but no evidence of deterioration in glucose tolerance (2-h glucose 9.1 vs 8.6 mmol/l p=0.50) or reduced beta cell function (log EIR 1.40 vs 1.26, p=0.11) compared with offspring born to glucokinase fathers., Conclusions/interpretation: The marked increase in birthweight shows that offspring born to affected mothers were exposed to increased glycaemia in utero. Despite this, there was no evidence of altered beta cell function or glucose tolerance. As previous human examples of marked programming by hyperglycaemia in utero have been in genetically predisposed offspring, we propose that our finding reflects the lack of genetic predisposition in the offspring to progressive beta cell dysfunction.

Mutations in the gene encoding hepatocyte nuclear factor (HNF)1beta result in maturity-onset diabetes of the young-(MODY)5, by impairing insulin secretory responses and, possibly, by reducing beta-cell mass. The functional role of HNF1beta in normal beta-cells is poorly understood; therefore, in the present study, wild-type (WT) HNF1beta, or one of two naturally occurring MODY5 mutations (an activating mutation, P328L329del, or a dominant-negative form, A263insGG) were conditionally expressed in the pancreatic beta-cell line, insulin-1 (INS-1), and the functional consequences examined. Surprisingly, overexpression of the dominant-negative mutant did not modify any of the functional properties of the cells studied (including insulin secretion, cell growth and viability). By contrast, expression of WT HNF1beta was associated with a time- and dose-dependent inhibition of INS-1 cell proliferation and a marked increase in apoptosis. Induction of WT HNF1beta also inhibited the insulin secretory response to nutrient stimuli, membrane depolarisation or activation of protein kinases A and C and this correlated with a significant decrease in pancrease-duodenum homeobox-1 protein levels. The attenuation of insulin secretion was, however, dissociated from the inhibition of proliferation and loss of viability, since expression of the P328L329del mutant led to a reduced rate of cell proliferation, but failed to induce apoptosis or to alter insulin secretion. Taken together, the present results suggest that mature rodent beta-cells are sensitive to increased expression of WT HNF1beta and they imply that the levels of this protein are tightly regulated to maintain secretory competence and cell viability.

Defining the molecular genetics of diabetes gives new insight into the underlying etiology and so should help improve treatment. The genetic etiology is now known for most patients with beta-cell monogenic diabetes, allowing genetic classification. We review how this genetic knowledge alters treatment. Patients with a glucose-sensing beta-cell defect due to glucokinase mutations have regulated, mild, fasting hyperglycemia. Oral hypoglycemic agents or low-dose insulin rarely improve glycemic control. Patients with hepatic nuclear factor-1alpha (HNF1alpha) mutations have progressive beta-cell deterioration and require treatment. HNF1alpha patients are 4 times more sensitive to sulfonylureas than matched type 2 diabetic patients. This is partly due to greater insulin secretion, reflecting the fact that the defect in HNF1alpha deficiency precedes the K(ATP) channel where sulfonylureas act. HNF1beta is expressed in pancreatic stem cells before differentiation into endocrine or exocrine cells, so patients with HNF1beta mutations have reduced pancreatic development, resulting in early-onset diabetes and exocrine dysfunction. These patients usually rapidly require insulin and are not sensitive to sulfonylureas. Thirty-five to 50% of patients diagnosed with diabetes before 6 months have a mutation in Kir6.2. The mutated KATP channel in these patients does not close in response to increased ATP concentrations, but can be closed when sulfonylureas bind to the sulfonylurea receptor 1 subunit of the channel by an ATP-independent route. These patients are usually insulin dependent, but have excellent glycemic control on high-dose sulfonylureas tablets. In conclusion, the defining of molecular genetic etiology in monogenic diabetes has identified several specific beta-cell defects, and these are critical in determining the response to treatment.

Aims/hypothesis: Heterozygous mutations in the gene of the transcription factor hepatocyte nuclear factor 4alpha (HNF-4alpha) are considered a rare cause of MODY with only 14 mutations reported to date. The description of the phenotype is limited to single families. We investigated the genetics and phenotype of HNF-4alpha mutations in a large European Caucasian collection., Methods: HNF-4alpha was sequenced in 48 MODY probands, selected for a phenotype of HNF-1alpha MODY but negative for HNF-1alpha mutations. Clinical characteristics and biochemistry were compared between 54 HNF-4alpha mutation carriers and 32 familial controls from ten newly detected or previously described families., Results: Mutations in HNF-4alpha were found in 14/48 (29%) probands negative for HNF-1alpha mutations. The mutations found included seven novel mutations: S34X, D206Y, E276D, L332P, I314F, L332insCTG and IVS5nt+1G>A. I314F is the first reported de novo HNF-4alpha mutation. The average age of diagnosis was 22.9 years with frequent clinical evidence of sensitivity to sulphonylureas. Beta cell function, but not insulin sensitivity, was reduced in diabetic mutation carriers compared to control subjects (homeostasis model assessment of beta cell function 29% p<0.001 vs controls). HNF-4alpha mutations were associated with lower apolipoprotein A2 (p=0.001), A1 (p=0.04) and total HDL-cholesterol (p=0.02) than in control subjects. However, in contrast to some previous reports, levels of triglycerides and apolipoprotein C3 were normal., Conclusions/interpretation: HNF-4alpha mutations are common when no HNF-1alpha mutation is found in strictly defined MODY families. The HNF-4alpha clinical phenotype and beta cell dysfunction are similar to HNF-1alpha MODY and are associated with reduced apolipoprotein A2 levels. We suggest that sequencing of HNF-4alpha should be performed in patients with clinical characteristics of HNF-1alpha MODY in whom mutations in HNF-1alpha are not found.

Neonatal diabetes can either remit and hence be transient or else may be permanent. These two phenotypes were considered to be genetically distinct. Abnormalities of 6q24 are the commonest cause of transient neonatal diabetes (TNDM). Mutations in KCNJ11, which encodes Kir6.2, the pore-forming subunit of the ATP-sensitive potassium channel (K(ATP)), are the commonest cause of permanent neonatal diabetes (PNDM). In addition to diabetes, some KCNJ11 mutations also result in marked developmental delay and epilepsy. These mutations are more severe on functional characterization. We investigated whether mutations in KCNJ11 could also give rise to TNDM. We identified the three novel heterozygous mutations (G53S, G53R, I182V) in three of 11 probands with clinically defined TNDM, who did not have chromosome 6q24 abnormalities. The mutations co-segregated with diabetes within families and were not found in 100 controls. All probands had insulin-treated diabetes diagnosed in the first 4 months and went into remission by 7-14 months. Functional characterization of the TNDM associated mutations was performed by expressing the mutated Kir6.2 with SUR1 in Xenopus laevis oocytes. All three heterozygous mutations resulted in a reduction in the sensitivity to ATP when compared with wild-type (IC(50) approximately 30 versus approximately 7 microM, P-value for is all <0.01); however, this was less profoundly reduced than with the PNDM associated mutations. In conclusion, mutations in KCNJ11 are the first genetic cause for remitting as well as permanent diabetes. This suggests that a fixed ion channel abnormality can result in a fluctuating glycaemic phenotype. The multiple phenotypes associated with activating KCNJ11 mutations may reflect their severity in vitro.

Aims: Knockout mice lacking both copies of the hepatocyte nuclear factor 1 (HNF1) gene have altered serum levels of amino acids and generalized aminoaciduria. The aim of our study was to test whether alterations in serum amino acid levels were found in patients with mutations in the hepatocyte nuclear factor-1 alpha (HNF-1alpha) gene compared with controls., Methods: Fasting serum from 20 patients with HNF-1alpha mutations and 20 age, sex and body mass index-matched controls was analysed for 16 amino acids. Means were compared between the two groups and Z scores calculated., Results: There was no significant difference between patients with HNF-1alpha mutations and controls in serum levels of phenylalanine, arginine, citrulline or lysine as suggested by knockout mice models. Although serum levels of eight amino acids were different in the two groups, these were not significant after Bonferroni correction., Conclusions: The alterations in serum amino acid levels seen in mice models are not seen in patients with mutations in the HNF-1alpha gene. This suggests differences in mouse and man in the regulation of amino acid transport and has not provided us with a phenotypic marker to use before confirmatory genetic testing., (Copyright 2004 Diabetes UK)

Objective: Mutations in the highly homologous transcription factors hepatocyte nuclear factor (HNF)-1alpha and -1beta cause maturity-onset diabetes of the young types 3 and 5, respectively. Diabetes due to HNF-1alpha mutations is well characterized. However, physiological assessment of the HNF-1beta phenotype is limited. We aimed to test the hypothesis that the diabetes phenotype due to HNF-1beta mutations is similar to that in HNF-1alpha., Research Design and Methods: Fasting biochemistry and a tolbutamide-modified intravenous glucose tolerance test (IVGTT) were compared in matched HNF-1beta, HNF-1alpha, type 2 diabetic, and control subjects. Homeostasis model assessment indexes were determined from fasting insulin and glucose. The peak measures for the insulin increment after tolbutamide and for the insulin increment after glucose were determined from the IVGTT., Results: The HNF-1beta patients showed a 2.4-fold reduction in insulin sensitivity compared with the HNF-1alpha patients (P = 0.001) with fasting insulin concentrations 2.7-fold higher (P = 0.004). HNF-1beta patients had lower HDL cholesterol (1.17 vs. 1.46 mmol/l; P = 0.009) and higher triglyceride (2.2 vs. 1.35 mmol/l; P = 0.015) levels than HNF-1alpha patients. The HNF-1beta patients had similar beta-cell responses to tolbutamide and glucose as the type 2 diabetic patients, but in the HNF-1alpha patients, the tolbutamide response was considerably increased relative to the response to glucose (P = 0.002)., Conclusions: HNF-1beta patients have a different diabetes phenotype than HNF-1alpha patients. Those with HNF-1beta mutations have hyperinsulinemia and associated dyslipidemia consistent with insulin resistance and may have a different beta-cell defect. This suggests that despite considerable homology and a shared binding site, HNF-1alpha and HNF-1beta have a different role in maintaining normal glucose homeostasis. This result suggests a new etiological pathway for insulin resistance involving HNF-1beta.

Hepatocyte nuclear factor-1a (HNF-1alpha) is a transcription factor that plays an important role in regulation of gene expression in pancreatic beta-cells, intestine, kidney, and liver. Heterozygous mutations in the HNF-1alpha gene are responsible for maturity-onset diabetes of the young (MODY3), which is characterized by pancreatic beta-cell-deficient insulin secretion. HNF-1alpha is a major transcriptional regulator of many genes expressed in the liver. However, no liver defect has been identified in individuals with HNF-1alpha mutations. In this study, we show that Hnf-1alpha is a potent transcriptional activator of the gene encoding apolipoprotein M (apoM), a lipoprotein that is associated with the HDL particle. Mutant Hnf-1alpha(-/-) mice completely lack expression of apoM in the liver and the kidney. Serum apoM levels in Hnf-1alpha(+/-) mice are reduced approximately 50% compared with wild-type animals and are absent in the HDL and HDLc fractions of Hnf-1alpha(-/-). We analyzed the apoM promoter and identified a conserved HNF-1 binding site. We show that Hnf-1alpha is a potent activator of the apoM promoter, that a specific mutation in the HNF-1 binding site abolished transcriptional activation of the apoM gene, and that Hnf-1alpha protein can bind to the Hnf-1 binding site of the apoM promoter in vitro. To investigate whether patients with mutations in HNF-1alpha mutations (MODY3) have reduced serum apoM levels, we measured apoM levels in the serum of nine HNF-1alpha/MODY3 patients, nine normal matched control subjects (HNF-1alpha(+/+)), and nine HNF-4alpha/MODY1 subjects. Serum levels of apoM were decreased in HNF-1alpha/MODY3 subjects when compared with control subjects (P < 0.02) as well as with HNF-4alpha/MODY1 subjects, indicating that HNF-1alpha haploinsufficiency rather than hyperglycemia is the primary cause of decreased serum apoM protein concentrations. This study demonstrates that HNF-1alpha is required for apoM expression in vivo and that heterozygous HNF-1alpha mutations lead to an HNF-1alpha-dependent impairment of apoM expression. ApoM levels may be a useful serum marker for the identification of MODY3 patients.

Background: Familial juvenile hyperuricemic nephropathy (FJHN) is a dominantly inherited condition characterized by young-onset hyperuricemia, gout, and renal disease. The etiologic genes are unknown, although a locus on chromosome 16 has been identified in some kindreds. Mutations in the gene encoding hepatocyte nuclear factor (HNF)-1beta have been associated with dominant inheritance of a variety of disorders of renal development, particularly renal cystic disease and early onset diabetes; hyperuricemia has been reported in some kindreds., Methods: To assess a possible role for the HNF-1beta gene in some FJHN kindreds we sequenced the HNF-1beta gene in subjects from three unrelated FJHN families with atypical features of renal cysts or abnormalities of renal development. We also compared serum urate levels in subjects with HNF-1beta mutations with populations of controls, type 2 diabetic subjects, and subjects with mild chronic renal failure without HNF-1beta mutations., Results: A splice-site mutation in intron 2, designated IVS2+1G>T, showed complete co-segregation with FJHN in one family with diabetes. Serum urate levels were significantly higher in the HNF-1beta subjects compared with the normal control subjects (384 micromol/L vs. 264 micromol/L, P = 0.002) and the type 2 diabetic subjects (397 micromol/L vs. 271 micromol/L, P = 0.01). Comparison of serum urate levels in the HNF-1beta subjects with gender-matched subjects with renal impairment of other causes did not reach significance (402 micromol/L vs. 352 micromol/L, P = 0.2)., Conclusion: Hyperuricemia and young-onset gout are consistent features of the phenotype associated with HNF-1beta mutations, but the mechanism is uncertain. Families with HNF-1beta mutations may fit diagnostic criteria for FJHN. Identification of HNF-1beta patients by recognizing the features of diabetes and disorders of renal development is important in resolving the genetic heterogeneity in FJHN.

After renal transplantation for congenital cystic kidney disease of unknown origin, a 14-year-old boy, who was previously normoglycemic, had "steroid-induced" diabetes mellitus, which was treated with insulin. Transplant failure from chronic rejection and subsequent transplant nephrectomy allowed discontinuation of corticosteroids, the gradual withdrawal of insulin and normoglycemia. The recent description of renal cysts and diabetes (RCAD) syndrome and a strong paternal family history of early-onset diabetes mellitus prompted genetic screening of the hepatocyte nuclear factor-1beta gene. A novel heterozygous frameshift mutation in exon 1 was identified, adding to the 12 kindreds thus far described. This case highlights the unmasking of the hyperglycemic component of the RCAD syndrome in the immediate postoperative period after renal transplantation and emphasizes the pleiotropic manifestations of this important genetic kidney disease., (Copyright 2002 by the National Kidney Foundation, Inc.)

Mutations in the beta-cell genes encoding the glycolytic enzyme glucokinase (GCK) and the transcription factor hepatocyte nuclear factor (HNF)-1alpha are the most common causes of maturity-onset diabetes of the young (MODY). Studying patients with mutations in these genes gives insights into the functions of these two critical beta-cell genes in humans. We studied 178 U.K. and French MODY family members, including 45 GCK mutation carriers and 40 HNF-1alpha mutation carriers. Homeostasis model assessment of fasting insulin and glucose showed reduced beta-cell function in both GCK (48% controls, P<0.0001) and HNF-1alpha (42% controls, P<0.0001). Insulin sensitivity was similar to that of control subjects in the GCK subjects (93% controls, P = 0.78) but increased in the HNF-1alpha subjects (134.5% controls, P = 0.005). The GCK patients showed a similar phenotype between and within families with mild lifelong fasting hyperglycemia (fasting plasma glucose [FPG] 5.5-9.2 mmol/l, interquartile [IQ] range 6.6-7.4), which declined slightly with age (0.017 mmol/l per year) and rarely required pharmacological treatment (17% oral hypoglycemic agents, 4% insulin). HNF-1alpha patients showed far greater variation in fasting glucose both between and within families (FPG 4.1-18.5 mmol/l, IQ range 5.45-10.4), with a marked deterioration with age (0.06 mmol/l per year), and 59% of patients required treatment with tablets or insulin. Proinsulin-to-insulin ratios are increased in HNF-1alpha subjects (29.5%) but not in GCK (18.5%) subjects. In an oral glucose tolerance test, the 0- to 120-min glucose increment was small in GCK patients (2.4+/-1.8 mmol/l) but large in HNF-1alpha patients (8.5+/-3.0 mmol/l, P< 0.0001). This comparison shows that the clear clinical differences in these two genetic subgroups of diabetes reflect the quantitative and qualitative differences in beta-cell dysfunction. The defect in GCK is a stable defect of glucose sensing, whereas the HNF-1alpha mutation causes a progressive defect that alters beta-cell insulin secretion directly rather than the sensing of glucose.

Introduction: Maturity-onset diabetes of the young (MODY) is characterized by autosomal dominantly inherited, early-onset, non-insulin-dependent diabetes. Mutations in the hepatocyte nuclear factor (HNF)-1alpha gene are the commonest cause of MODY. Individual patients with HNF-1alpha mutations have been reported as being unusually sensitive to the hypoglycaemic effects of sulphonylurea therapy. We report three patients, attending a single clinic, with HNF-1alpha mutations that show marked hypersensitivity to sulphonylureas., Case Reports: In cases 1 and 2 there were marked changes in HbA1c on cessation (4.4% and 5.8%, respectively) and reintroduction (5.0% and 2.6%) of sulphonylureas. Case 3 had severe hypoglycaemic symptoms on the introduction of sulphonylureas despite poor glycaemic control and was shown with a test dose of 2.5 mg glibenclamide to have symptomatic hypoglycaemia (blood glucose 2 mmol/l) after 4 h despite eating., Conclusions: HNF-1alpha MODY diabetic subjects are more sensitive to sulphonylureas than Type 2 diabetic subjects and this is seen in different families, with different mutations and may continue up to 13 years from diagnosis. This is an example of pharmacogenetics, with the underlying aetiological genetic defect altering the pharmacological response to treatment. The present cases suggest that in HNF-1alpha MODY patients: (i) sulphonylureas can dramatically improve glycaemic control and should be considered as initial treatment for patients with poor glycaemic control on an appropriate diet; (ii) hypoglycaemia may complicate the introduction of sulphonylureas and therefore very low doses of short acting sulphonylureas should be used initially; and (iii) cessation of sulphonylureas should be undertaken cautiously as there may be marked deterioration in glycaemic control.