What complications arise with an individual who exercises whilst taking metformin?

Because metformin is an “insulin sensitizer, ” it is not likely to cause exercise-related hypoglycemia (low blood sugar), which is typically one of the greatest concerns with some of the other oral agents for diabetes. People taking metformin who also engage in endurance exercise such as marathon running or extended hiking may experience difficulty regulating blood sugar levels due to metformin’s blocking effect on liver glycogen release (an important regulatory component to endurance exercise). Typical duration exercise bouts are not likely to cause this however. People with diabetes would be wise to check blood sugars around (and perhaps even during) exercise; carry a quick acting source of carbohydrate to treat/prevent hypoglycemia; wear/carry diabetes medical identification; exercise with a partner or carry a cell phone; and check with their physician prior to beginning an exercise program.

DMW