Clinical Impact of the TCF7L2 Gene rs7903146 Type 2 Diabetes Mellitus Risk Polymorphism in Women with Gestational Diabetes Mellitus: Impaired Glycemic Control and Increased Need of Insulin Therapy

Background The single nucleotide polymorphism in TCF7L2 rs7903146 is associated with an increased risk of type 2 diabetes mellitus and gestational diabetes mellitus. Mechanisms by which this mutation acts, and its impact on the clinical course of the diseases remain unclear. Here we investigated the clinical impact of the T risk allele in women with gestational diabetes mellitus. Methods We genotyped the CST polymorphism in 164 Caucasian women with GDM (German n =114; Greek n =50). The impact of the T allele on the results of the 75g oral-glucose-tolerance-test, and on the required therapy (diet/lifestyle or insulin) was investigated. Results During oral-glucose-tolerance-test, women harboring the T allele displayed significantly higher glucose values at 60 min (p = 0.034) and were more likely to require insulin therapy even after adjusting for confounders, such as BMI and age. Conclusion These results provide evidence that the T risk allele in TCF7L2 rs7903146 is associated with failure in early postprandial glycemic control and requirement of insulin therapy in women with gestational diabetes mellitus, even after adjusting for confounding factors such BMI and age.