Serine racemase rs391300 G/A polymorphism influences the therapeutic efficacy of metformin in Chinese patients with diabetes mellitus type 2

1. The aim of this study was to investigate the association of the serine racemase (SRR) rs391300 G/A polymorphism with the risk of diabetes mellitus type 2 (T2DM) and to assess the impacts of the polymorphism on the therapeutic efficacy of metformin in Chinese patients. 2. A case-control study of 402 patients with T2DM and 171 healthy controls was conducted. The SRR rs391300 polymorphism was genotyped in all participants using the ABI 3700 automated sequencer. Forty-four recent-onset T2DM patients with different rs391300 genotypes were selected to receive 500 mg metformin orally daily for 12 consecutive weeks as monotherapy. Serum fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated haemoglobin (HbA1c), fasting serum insulin (FINS), postprandial serum insulin (PINS), triglycerol (TG), cholesterol (CHO), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), homeostasis model assessment for insulin resistance (HOMA-IR), and body mass index (BMI) were determined before and after metformin treatment. 3. The distribution frequencies of rs391300 were in agreement with Hardy-Weinberg equilibrium (P0.05). After treatment with metformin, the values of BMI, FPG, PPG, PINS, HbA1c, CHO, and TG decreased significantly (P0.01), whereas FINS increased (P0.001), in patients with T2DM. Patients with the GA or AA genotype of rs391300 showed better improvements in the levels of FPG, PPG, and CHO (P0.05) than individuals with the GG genotype. 4. The SRR rs391300 polymorphism was associated with the therapeutic efficacy of metformin in Chinese patients with T2DM.