Whether or not a diabetic should eat before or after exercise depends on at least five factors, says a leading expert on diabetes.

“The answer to this question is, ‘It depends,’” says Sheri Colberg, PhD, Professor Emerita, Exercise Science, Old Dominion University, founder of Diabetes Motion, and one of the world’s leading experts on diabetes and exercise.

Dr. Colberg continues, “People with diabetes may or may not need any food/drink for exercise.”

Eating Before or After a Workout: Factors that Influence Diabetes

Dr. Colberg explains, “It depends on whether they use insulin (and when they last took any, if they do), when they last ate, what their starting blood glucose is, what type of activity they’re doing (intensity, duration, etc.), the time of day they do it, and more.

“As far as performance goes, if you have diabetes and exercise for more than an hour, you may benefit from fueling like other athletes (without diabetes) would do for their athletic endeavors, which often includes during the activity as well as before and after.”

This would included activities like mountain biking, hiking, group fitness classes and lifting weights.

“If you take insulin, you may need to take some to cover what you eat, or you may not any or much, depending on other factors.

“Almost everyone can benefit from refueling after exercise (to restore their muscle glycogen or carbohydrate stores), but often that can be done with meals and not special food intake. It’s complicated!”

With all that said, it will not hurt if the person with diabetes has an adequate supply of quick-acting carbs on hand at the gym – just in case.

And a meal within an hour of a hard workout that includes a high quality protein source is a universal recommendation by most fitness experts, especially if you’re trying to build muscle. 

The mission of Diabetes Motion is to provide practical guidance about blood glucose management to active diabetics. Dr. Sheri Colberg is the author of “Diabetes & Keeping Fit for Dummies.” 
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


Top image: ©Lorra Garrick