Age at onset of obesity, transcription factor 7-like 2 (TCF7L2) rs7903146 polymorphism, adiponectin levels and the risk of type 2 diabetes in obese patients

INTRODUCTION: Interaction between obesity and genetic factors involved in the regulatory pathways of glucose homeostasis may play a significant role in diabetes development in the obese. The aim of this study was to investigate the associations between the TCF7L2 rs7903146 polymorphism, adiponectin levels, age at onset of obesity and the occurrence of type 2 diabetes (T2D) in a sample of obese Polish adults. MATERIAL AND METHODS: A total of 474 unrelated obese subjects were included in this study. Real-time PCR was used to detect the TCF7L2 rs7903146 polymorphism. Serum level of adiponectin was determined by the ELISA method. Standard assays were used to measure total cholesterol, HDL cholesterol, triglycerides, glucose and HbA(1c) concentrations. We used multiple logistic regression to identify factors associated with type 2 diabetes. RESULTS: We found that the T allele of rs7903146 was significantly associated with T2D risk (odds ratio of 1.59 for T allele, p = 0.005). This association persisted after adjusting for confounders in the recessive model (odds ratio of 3.54 for TT genotype, p = 0.011). Serum adiponectin levels were significantly lower in diabetic subjects than in nondiabetic individuals (3.6 vs. 5.6 µg/ml, p < 0.001). Participants who were obese at age ≥ 20 years had significantly higher odds of having T2D (OR = 4.94) than those with the onset of obesity before 20 years (p < 0.001). CONCLUSIONS: Our study highlights the significance of the relationship between the TCF7L2 polymorphism, a person’s age at onset of obesity and the prevalence of T2D, and confirms lower adiponectin levels in obese diabetics in comparison to obese nondiabetics.