Effects of genetic variants of organic cation transporters on metformin response in newly diagnosed patients with type 2 diabetes.

Type 2 diabetes mellitus (T2DM) is a chronic disease that affects millions of people worldwide. Metformin is the optimal initial therapy for patients with T2DM. Genetic factors play a vital role in metformin response, including variations in drug efficacy and potential side effects. To determine the effects of genetic variants of multidrug and toxin extrusion protein 2 (MATE2), ataxia telangiectasia mutated (ATM), and serine/threonine kinase 11 (STK11) genes on metformin response in a cohort of Saudi patients. This prospective observational study included 76 T2DM newly diagnosed Saudi patients treated with metformin monotherapy and 80 control individuals. Demographic data, lipid profiles, creatinine levels, and hemoglobin A1c (HbA1c) levels were collected before and after treatment. All participants were genotyped for 5 single-nucleotide polymorphisms (SNPs), including rs4621031, rs34399035, rs2301759, rs1800058, and rs11212617, using TaqMan R genotyping assays. This study included 156 subjects. The subjects' mean ± SD age was 50.4 ± 10.14 years. The difference in HbA1c levels in T2DM after treatment ranged from -1.20% to 8.8%, with a mean value of 0.927 ± 1.73%. In general, 73.7% of the patients with T2DM showed an adequate response to metformin (HbA1c < 7%). STK11 (rs2301759) significantly affects the response to metformin in T2DM patients. In the rs2301759 single-nucleotide polymorphisms, the prevalence of an adequate response to metformin was significantly higher among patients with C/C and T/C genotypes than among non-responders (P = .021). However, no statistically significant associations were observed for the other tested SNPs. Our study provides evidence of an association between STK11 (rs2301759) and response to metformin in Saudi patients with T2DM. The need for targeted studies on specific gene-drug associations is emphasized, and further studies with a larger population should be conducted.