The Gene-Treatment Interaction of FTO‐rs9939609 Gene Polymorphism and Epigallocatechin-Gallate Intervention on Anthropometric Indices, Fasting Blood Sugar and Insulin Resistance/Sensitivity in Patients with Type 2 Diabetes Mellitus

The role of FTO-rs9939609 gene variants in response to the Epigallocatechin-Gallate (EGCG) intervention remains unclear. The present study aimed at investigating the gene-treatment interaction of FTO‐rs9939609 gene polymorphism and EGCG intervention on anthropometric indexes, fasting blood sugar, and insulin resistance/sensitivity in patients with Type 2 Diabetes Mellitus (T2DM). This double-blind, randomized, placebo-controlled study was conducted on 66 patients (aged 20 to 60 years) with T2DM in Iran, from August 2017 to March 2018. Individuals were randomly block allocated to three groups. Group 1 received 300 mg EGCG (n = 22, TT genotype), Group 2 received 300 mg EGCG (n = 22, AA + AT genotypes), Group 3 received the placebo (n = 22). Two months following the intervention, Waist-Hip Ratio (WHR), A Body Shape Index (ABSI), Fasting Blood Sugar (FBS), and insulin levels, as well as Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI) were evaluated. The FTO‐rs9939609 polymorphism was genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). In both EGCG groups, a significant reduction in WHR was observed after the intervention compared with baseline (P < 0.05), with no significant differences in other parameters. The FTO‐rs9939609 polymorphism showed no gene-treatment interaction in response to EGCG. This study suggests that administration of EGCG supplement for two months may provide anti-obesity effects in patients with T2DM. However, the FTO-rs9939609 polymorphism was not associated with the change in anthropometric and glycemic status after EGCG intervention.