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Effects of the diabetes linked TCF7L2 polymorphism in a representative older population.

ABSTRACT: BACKGROUND:A polymorphism in the transcription factor 7-like 2 (TCF7L2) gene has been found to be associated with type 2 diabetes in case-control studies. We aimed to estimate associations of the marker rs7903146 (C/T) polymorphism with fasting glucose, lipids, diabetes prevalence and complications in an older general population. METHODS:In total, 944 subjects aged > or = 65 years from the population representative InCHIANTI study were enrolled in this study. Those with fasting blood glucose of > or = 7 mmol/l or physician diagnosis were considered diabetic. Cut-off points for impaired fasting glucose (IFG) were > or = 5.6 mmol/l to < 7 mmol/l. RESULTS:In the general population sample, minor (T) allele carriers of rs7903146 had higher fasting blood glucose (FBG) (p = 0.028) but lower fasting insulin (p = 0.030) and HOMA2b scores (p = 0.001), suggesting poorer beta-cell function. T allele carriers also had smaller waist circumference (p = 0.009), lower triglyceride levels (p = 0.006), and higher high-density lipoprotein cholesterol (p = 0.008). The prevalence of diabetes or IFG was 32.4% in TT carriers and 23.3% in CC carriers; adjusted OR = 1.67 (95% confidence interval 1.05 to 2.65, p = 0.031). Within the diabetic and IFG groups, fewer T allele carriers had metabolic syndrome features (p = 0.047) or had experienced a myocardial infarction (p = 0.037). Conversely, T allele carriers with diabetes had poorer renal function (reduced 24-hour creatinine clearance, p = 0.013), and possibly more retinopathy (p = 0.067). Physician-diagnosed dementia was more common in the T carriers (in diabetes p = 0.05, with IFG p = 0.024). CONCLUSION:The TCF7L2 rs7903146 polymorphism is associated with lower insulin levels, smaller waist circumference, and lower risk lipid profiles in the general elderly population. Patients with diabetes who are carriers of the minor allele are less likely to have metabolic-syndrome features, but may experience more microvascular complications, although the number of cases was small. If replicated, these findings may have implications for developing treatment approaches tailored by genotype.

SUBMITTER: Melzer D

PROVIDER: S-EPMC1769391 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature

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Effects of the diabetes linked TCF7L2 polymorphism in a representative older population.

Melzer David D Murray Anna A Hurst Alison J AJ Weedon Michael N MN Bandinelli Stefania S Corsi Anna Maria AM Ferrucci Luigi L Paolisso Guiseppe G Guralnik Jack M JM Frayling Timothy M TM

BMC medicine 20061220

<h4>Background</h4>A polymorphism in the transcription factor 7-like 2 (TCF7L2) gene has been found to be associated with type 2 diabetes in case-control studies. We aimed to estimate associations of the marker rs7903146 (C/T) polymorphism with fasting glucose, lipids, diabetes prevalence and complications in an older general population.<h4>Methods</h4>In total, 944 subjects aged > or = 65 years from the population representative InCHIANTI study were enrolled in this study. Those with fasting bl ...[more]

PMID: 17181866

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Project description:BackgroundGlucagon-like peptide 1 (GLP-1) stimulates insulin secretion and reduces blood glucose in type 2 diabetes mellitus (T2DM). TCF7L2 rs7903146 polymorphism has been associated with decreased insulin secretion, reduced GLP-1 action, and possible impaired peripheral insulin sensitivity.ObjectivesTo evaluate the postprandial pancreatic hormone response in patients with T2DM carriers of the TCF7L2 variant rs7903146 (CT/TT) compared with noncarriers of this variant (CC) after treatment with the GLP-1 agonist exenatide.MethodsIntervention study. Patients with T2DM (n = 162) were genotyped for the TCF7L2 rs7903146 single nucleotide polymorphism (SNP). Individuals with CT/TT and CC genotypes were compared regarding basal serum levels of glucose, glycosylated hemoglobin A1C (HbA1c), HDL, uric acid, insulin, and C-peptide. A subset of 56 individuals was evaluated during a 500-calorie mixed-meal test with measurements of glucose, insulin, proinsulin, C-peptide and glucagon before and after treatment with exenatide for 8 weeks.ResultsPatients with genotypes CC and CT/TT presented similar glucose area under the curve (AUC) 0-180 min before treatment and a similar decrease after treatment (p < 0.001). Before exenatide, insulin levels at 30-120 min were higher in CT/TT versus CC subjects (p < 0.05). After treatment with exenatide, only CT/TT individuals demonstrated insulin reduction at 30-180 min during the meal test (p < 0.05). Patients with the CC genotype presented no differences in insulin concentrations before and after treatment. The areas under the glucagon curve between 0 and 180 min were similar before treatment and reduced after treatment in both groups (p < 0.001).ConclusionsThe presence of the TCF7L2 rs7903146 T allele in patients with T2DM was associated with increased secretion of insulin response to a mixed-meal test. Furthermore, after treatment with exenatide, only the carriers of the T allele showed significantly decreased postprandial plasma insulin peak levels comparing with non carriers.

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Effects of the diabetes linked TCF7L2 polymorphism in a representative older population.

Publications

Effects of the diabetes linked TCF7L2 polymorphism in a representative older population.

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