More effective glycaemic control by metformin in African Americans than in Whites in the prediabetic population

Abstract

Aim: Metformin, a first-line diabetes drug, delays the onset of type 2 diabetes in the prediabetic population; however, in prediabetic patients, differences in glycaemic response to metformin among racial groups are unknown. We aimed to compare glucose-lowering effects of metformin between Whites and African Americans (AAs).

Methods: We performed a secondary analysis using data from the diabetes prevention program, a multi-center randomized clinical trial, in which all participants were prediabetic. The metformin group (582 Whites and 210 AAs) received 850 mg of metformin twice daily, and was followed for 3 years.

Results: We found that after 6 months on metformin, Whites had a drop of 3.89 ± 0.39 (mg/dL, mean ± SEM) in the fasting plasma glucose level, significantly less than that in African Americans (6.04 ± 0.72, P=0.006); at years 1 and 2, the differences were also significant. Consistently, the linear mixed model showed that, within 1 year of metformin treatment, the rate in reduction of glucose levels was more pronounced in AAs than in Whites (P=0.025 following adjustment for age and sex).

Conclusions: Therefore, AAs have a better glycaemic response to metformin treatment than Whites in the prediabetic population.

Keywords: Diabetes prevention program; Metformin; Prediabetes.