Exercise Impact Lessened Slightly by Metformin in Prediabetes

Steven K. Malin, Ph.D., from the University of Massachusetts in Amherst, and colleagues evaluated the combined effects of exercise training and metformin on insulin sensitivity in men and women with prediabetes, compared with each treatment alone. A total of 32 men and women with prediabetes were assigned to any of four treatments for 12 weeks: placebo, 2000 mg per day metformin, exercise training with placebo (EP), or exercise training with metformin (EM) (eight patients in each group). Insulin sensitivity was measured before and after the treatment using a euglycemic hyperinsulinemic (80 mU/m²/min) clamp enriched with [6,6-²H] glucose. Repeated analysis of variance measures were used to compare the intervention related changes across the groups.

The investigators found that, compared to the placebo group, insulin sensitivity increased significantly in all three intervention groups: metformin, EP, and EM. The mean rise in insulin sensitivity was 25 to 30 percent higher after EP, but this increase was not significantly different compared to the increase after either metformin or EM.

"Insulin sensitivity was considerably higher after 12 weeks of exercise training and/or metformin in men and women with prediabetes. Subtle differences among condition means suggest that adding metformin blunted the full effect of exercise training," the authors write.

Diabetes Care, Oct. 31, 2011