Effect of metformin on exercise capacity in treatment naïve type 2 diabetes patients

Exercise capacity is decreased in diabetes mellitus due to impaired insulin sensitivity, endothelial dysfunction and mitochondrial dysfunction. The aim of the study was to evaluate the effect of metformin on exercise capacity in treatment naïve patients with type 2 diabetes mellitus.

Newly diagnosed type 2 diabetes mellitus patients were tested for baseline insulin resistance and exercise capacity, before starting on metformin. Exercise capacity was measured by incremental exercise testing in treadmill (ZAN 600 CPET system) using modified Bruce protocol at baseline, 6 weeks and 12 weeks following metformin therapy.

A total of 33 treatment naïve type 2 diabetes patients were enrolled of which 19 patients completed the study. There was no significant change in any of the exercise capacity parameters at the end of 12 weeks of metformin. Nevertheless, there was a significant improvement in VO₂/kg among those with insulin resistance as compared to those without insulin resistance.

Metformin monotherapy did not produce any change in exercise capacity in treatment naïve type 2 diabetes patients. However, a significant fall in exercise capacity (VO₂/kg) was observed in patients without insulin resistance as compared to those with insulin resistance at the end of 12 weeks of metformin therapy.