A recent study from researchers at Rutgers University suggests that the widely used diabetes medication metformin may reduce some of the key benefits associated with exercise. The findings indicate that adults taking metformin while engaging in physical activity experience less improvement in blood sugar control, blood vessel function, and aerobic fitness compared to those who exercise without the drug. The study was published in The Journal of Clinical Endocrinology & Metabolism last month.
Dr. Steven Malin, the lead author of the study and a professor in the Department of Kinesiology and Health at Rutgers, explained that metformin is the most commonly prescribed glucose-lowering medication globally. He cautioned, “It is not clear that taking both of these treatments together is best.” This uncertainty raises concerns that individuals may experience low energy levels and potentially face a decline in their overall health, leading to what Malin describes as “psychological defeat.”
The research involved a 16-week, double-blind trial with 72 adults at risk for metabolic syndrome—a cluster of conditions that includes high blood pressure and elevated blood sugar levels. Participants were divided into four groups, with two groups performing high- or low-intensity exercise alongside a placebo, while the other two groups engaged in the same workouts while taking 2,000 milligrams of metformin daily.
At the study’s conclusion, those who exercised without metformin exhibited significant improvements in vascular insulin sensitivity, indicating that their blood vessels were more responsive to insulin, allowing better delivery of oxygen and nutrients to muscles. In contrast, those taking metformin showed diminished gains. They also experienced less reduction in inflammation and fasting glucose levels. Researchers are exploring the possibility that metformin interferes with the body’s cellular adaptations to exercise.
Dr. Malin highlighted the relationship between blood vessel health and nutrient delivery. “Improved blood vessel function is key for delivering nutrients to tissues, like sugar,” he noted. “If the sugar cannot be delivered to the tissue, this might explain why muscles cannot use the sugar for energy as well in response to insulin.”
While the study’s results are compelling, researchers caution that the sample size was limited and primarily focused on adults at risk for metabolic syndrome, meaning the applicability to all individuals with diabetes remains uncertain. They emphasize that patients should not discontinue their use of metformin or exercise but instead consult with their healthcare providers to determine the best approach to treatment and physical activity.
Dr. David Cutler, a board-certified family medicine physician at Providence Saint John’s Health Center in California, provided context for the findings, stating that while the observed decrease in vascular insulin sensitivity is concerning, it must be weighed against the significant benefits of lowered blood sugar levels achieved through metformin. “The lowering of blood sugar results in lower risks of all diabetic complications like heart attack, stroke, kidney failure, blindness, and amputation,” he explained.
Cutler further noted that the results might be more relevant for individuals using metformin for reasons other than diabetes management, such as anti-aging or cancer prevention. He asserted, “For now, metformin should remain the first-line medication for treating type 2 diabetes.”
As the medical community continues to examine the interactions between metformin and exercise, the Rutgers research team is also planning future studies to investigate how different types of exercise, such as resistance or strength training, may interact with metformin. Additionally, they aim to explore whether adjusting the medication’s dosage or timing could mitigate the effects noted in this study.
The implications of this research highlight the importance of ongoing dialogue between patients and healthcare providers regarding treatment strategies, particularly for those managing diabetes or related health conditions.
