Metformin blunts increases in macrovascular and microvascular insulin sensitivity seen with exercise.

“is there additional benefit that comes from metformin or is this a drug that is better reserved for people who are not taking the maximum dose of the drug known as exercise that basically is my question”

“Adults performing low- or high-intensity aerobic exercise for 16 weeks while taking metformin (2,000 mg/day) showed no improvement in VO₂ max. Those on placebo improved by about 6% on average.”

“Metformin also blunted increases in macrovascular and microvascular insulin sensitivity seen with both exercise intensities, attenuated improvements in fasting blood glucose, and prevented gains in whole-body insulin sensitivity, even after high-intensity exercise.”