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An important question in human genetics is the extent to which genes causing monogenic forms of disease harbor common variants that may contribute to the more typical form of that disease. We aimed to comprehensively evaluate the extent to which common variation in the six known maturity-onset diabetes of the young (MODY) genes, which cause a monogenic form of type 2 diabetes, is associated with type 2 diabetes. Specifically, we determined patterns of common sequence variation in the genes encoding Gck, Ipf1, Tcf2, and NeuroD1 (MODY2 and MODY4-MODY6, respectively), selected a comprehensive set of 107 tag single nucleotide polymorphisms (SNPs) that captured common variation, and genotyped each in 4,206 patients and control subjects from Sweden, Finland, and Canada (including family-based studies and unrelated case-control subjects). All SNPs with a nominal P value <0.1 for association to type 2 diabetes in this initial screen were then genotyped in an additional 4,470 subjects from North America and Poland. Of 30 nominally significant SNPs from the initial sample, 8 achieved consistent results in the replication sample. We found the strongest effect at rs757210 in intron 2 of TCF2, with corrected P values <0.01 for an odds ratio (OR) of 1.13. This association was observed again in an independent sample of 5,891 unrelated case and control subjects and 500 families from the U.K., for an overall OR of 1.12 and a P value <10[sup -e] in >15,000 samples. We combined these results with our previous studies on HNF4α and TCF1 and explicitly tested for gene-gene interactions among these variants and with several known type 2 diabetes susceptibility loci, and we found no genetic interactions between these six genes. We conclude that although rare variants in these six genes explain most cases of MODY, common variants in these same genes contribute very modestly, if at all, to the common form of type 2 diabetes. Diabetes 56:685-693, 2007 [ABSTRACT FROM AUTHOR]

Background: People with type 1 diabetes are at elevated risk of mortality and cardiovascular disease, yet current guidelines do not consider age of onset as an important risk stratifier. We aimed to examine how age at diagnosis of type 1 diabetes relates to excess mortality and cardiovascular risk.Methods: We did a nationwide, register-based cohort study of individuals with type 1 diabetes in the Swedish National Diabetes Register and matched controls from the general population. We included patients with at least one registration between Jan 1, 1998, and Dec 31, 2012. Using Cox regression, and with adjustment for diabetes duration, we estimated the excess risk of all-cause mortality, cardiovascular mortality, non-cardiovascular mortality, acute myocardial infarction, stroke, cardiovascular disease (a composite of acute myocardial infarction and stroke), coronary heart disease, heart failure, and atrial fibrillation. Individuals with type 1 diabetes were categorised into five groups, according to age at diagnosis: 0-10 years, 11-15 years, 16-20 years, 21-25 years, and 26-30 years.Findings: 27 195 individuals with type 1 diabetes and 135 178 matched controls were selected for this study. 959 individuals with type 1 diabetes and 1501 controls died during follow-up (median follow-up was 10 years). Patients who developed type 1 diabetes at 0-10 years of age had hazard ratios of 4·11 (95% CI 3·24-5·22) for all-cause mortality, 7·38 (3·65-14·94) for cardiovascular mortality, 3·96 (3·06-5·11) for non-cardiovascular mortality, 11·44 (7·95-16·44) for cardiovascular disease, 30·50 (19·98-46·57) for coronary heart disease, 30·95 (17·59-54·45) for acute myocardial infarction, 6·45 (4·04-10·31) for stroke, 12·90 (7·39-22·51) for heart failure, and 1·17 (0·62-2·20) for atrial fibrillation. Corresponding hazard ratios for individuals who developed type 1 diabetes aged 26-30 years were 2·83 (95% CI 2·38-3·37) for all-cause mortality, 3·64 (2·34-5·66) for cardiovascular mortality, 2·78 (2·29-3·38) for non-cardiovascular mortality, 3·85 (3·05-4·87) for cardiovascular disease, 6·08 (4·71-7·84) for coronary heart disease, 5·77 (4·08-8·16) for acute myocardial infarction, 3·22 (2·35-4·42) for stroke, 5·07 (3·55-7·22) for heart failure, and 1·18 (0·79-1·77) for atrial fibrillation; hence the excess risk differed by up to five times across the diagnosis age groups. The highest overall incidence rate, noted for all-cause mortality, was 1·9 (95% CI 1·71-2·11) per 100 000 person-years for people with type 1 diabetes. Development of type 1 diabetes before 10 years of age resulted in a loss of 17·7 life-years (95% CI 14·5-20·4) for women and 14·2 life-years (12·1-18·2) for men.Interpretation: Age at onset of type 1 diabetes is an important determinant of survival, as well as all cardiovascular outcomes, with highest excess risk in women. Greater focus on cardioprotection might be warranted in people with early-onset type 1 diabetes.Funding: Swedish Heart and Lung Foundation. [ABSTRACT FROM AUTHOR]

Objective: Identifying maturity-onset diabetes of the young (MODY) in pediatric populations close to diabetes diagnosis is difficult. Misdiagnosis and unnecessary insulin treatment are common. We aimed to identify the discriminatory clinical features at diabetes diagnosis of patients with glucokinase (GCK), hepatocyte nuclear factor-1A (HNF1A), and HNF4A MODY in the pediatric population., Research Design and Methods: Swedish patients ( n = 3,933) aged 1-18 years, diagnosed with diabetes May 2005 to December 2010, were recruited from the national consecutive prospective cohort Better Diabetes Diagnosis. Clinical data, islet autoantibodies (GAD insulinoma antigen-2, zinc transporter 8, and insulin autoantibodies), HLA type, and C-peptide were collected at diagnosis. MODY was identified by sequencing GCK , HNF1A , and HNF4A , through either routine clinical or research testing., Results: The minimal prevalence of MODY was 1.2%. Discriminatory factors for MODY at diagnosis included four islet autoantibody negativity (100% vs. 11% not-known MODY; P = 2 × 10 -44 ), HbA 1c (7.0% vs. 10.7% [53 vs. 93 mmol/mol]; P = 1 × 10 -20 ), plasma glucose (11.7 vs. 26.7 mmol/L; P = 3 × 10 -19 ), parental diabetes (63% vs. 12%; P = 1 × 10 -15 ), and diabetic ketoacidosis (0% vs. 15%; P = 0.001). Testing 303 autoantibody-negative patients identified 46 patients with MODY (detection rate 15%). Limiting testing to the 73 islet autoantibody-negative patients with HbA 1c <7.5% (58 mmol/mol) at diagnosis identified 36 out of 46 (78%) patients with MODY (detection rate 49%). On follow-up, the 46 patients with MODY had excellent glycemic control, with an HbA 1c of 6.4% (47 mmol/mol), with 42 out of 46 (91%) patients not on insulin treatment., Conclusions: At diagnosis of pediatric diabetes, absence of all islet autoantibodies and modest hyperglycemia (HbA 1c <7.5% [58 mmol/mol]) should result in testing for GCK, HNF1A, and HNF4A MODY. Testing all 12% patients negative for four islet autoantibodies is an effective strategy for not missing MODY but will result in a lower detection rate. Identifying MODY results in excellent long-term glycemic control without insulin., (© 2019 by the American Diabetes Association.)

Rare mutations in the glucokinase (GCK) gene cause fasting hyperglycemia and considerably influence birth weight when present in a mother or her offspring. The role of common variation of GCK is uncertain. A polymorphism at position -30 of the GCK beta-cell-specific promoter, present in 30% of the population, has been variably associated with type 2 diabetes and diabetes-related quantitative traits. Using 1,763 U.K. Caucasian normoglycemic adult subjects, we demonstrated that the A allele at GCK(-30) is associated with a 0.06-mmol/l increase in fasting plasma glucose (FPG) (P = 0.003). The A allele was also associated with an increase in FPG in 755 women who were 28 weeks pregnant (0.075 mmol/l, P = 0.003). We then went on to analyze the effect of GCK(-30) on birth weight using 2,689 mother/child pairs. The presence of the A allele in the mother was associated with a 64-g (25-102 g) increase in offspring birth weight (P = 0.001). We did not detect a fetal genotype effect. The increase in offspring birth weight in the 30% of mothers carrying an A allele at GCK(-30) is likely to reflect an elevated FPG during pregnancy. This study establishes that common genetic variation, in addition to rare mutations and environmental factors, can affect both FPG and birth weight.