Overview
- In a 16-week, double-blind trial of 72 adults at risk for metabolic syndrome, metformin reduced several improvements typically seen with training compared with exercise plus placebo.
- Participants on metformin showed smaller gains in vascular insulin sensitivity and aerobic fitness, with less favorable changes in fasting glucose and inflammation markers.
- The blunting effect appeared across both high-intensity and low-intensity programs, indicating exercise intensity did not offset the interaction.
- Researchers point to a possible mitochondrial mechanism and report study limits that include short duration, loss of some imaging data, an older predominantly female sample, and vessel measures taken in the arm.
- Independent clinicians caution that metformin remains first-line therapy for type 2 diabetes and advise patients not to stop the drug or exercise without medical guidance.