Diabetes Drug Metformin May Reduce Exercise Benefits, Study Finds
A new study suggests that metformin, a common diabetes medication, might diminish some of the key benefits of exercise for patients, potentially affecting blood sugar control and fitness gains. Researchers from Rutgers University found that adults taking metformin during exercise experienced smaller improvements in vascular function and aerobic fitness compared to those who exercised without the drug.
The findings, published in *The Journal of Clinical Endocrinology & Metabolism*, add to growing evidence that while both metformin and exercise improve blood sugar control and heart health, their combination may dull some of the positive effects of physical activity. Lead study author Steven Malin, a professor at Rutgers’ School of Arts and Sciences, emphasized the need for further research to understand the underlying mechanisms.
Nearly 35 million Americans have Type 2 diabetes, and millions more worldwide take metformin for blood sugar control or experimental anti-aging uses. The 16-week, double-blind trial followed 72 adults at risk for metabolic syndrome, splitting them into four groups—two performing high- or low-intensity exercise with a placebo and two performing the same workouts with 2,000 milligrams of metformin daily.
At the end of the study, those who exercised without the drug showed clear improvements in vascular insulin sensitivity, indicating better blood vessel response to insulin and enhanced nutrient delivery to muscles. However, when metformin was added, these gains were mitigated. Participants also experienced less reduction in inflammation and fasting glucose levels, though the exact reasons remain unclear, with researchers suggesting a potential interference with the body’s adaptation to exercise at a cellular level.
Malin noted that the study’s results may not apply universally to all diabetics, as it focused on adults at risk for metabolic syndrome. He urged individuals to consult with healthcare providers to ensure they’re receiving the best combination of treatment and activity. Future studies should explore ways to preserve the benefits of both therapies, with the Rutgers team now investigating whether metformin interacts differently with resistance training and if adjusting dosage or timing could reduce its impact.
Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center, provided context, emphasizing that while the small decline in vascular insulin sensitivity is noteworthy, it must be weighed against the significant benefits of metformin in lowering blood sugar levels. This reduction in blood sugar lowers the risk of complications like heart attacks, strokes, kidney failure, blindness, and amputation. Cutler recommended that metformin remain the first-line treatment for Type 2 diabetes but noted the findings may be more relevant to individuals using the drug for non-diabetic purposes such as anti-aging or cancer prevention.