Having diabetes is no reason to shy away from high intensity interval training (HIIT), and in fact, this form of anaerobic exercise can be a superb way to help control blood sugar.

Duration of HIIT for Diabetics
“There’s no definitive answer as to how long the high intensity intervals should last,” 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.

“Different studies have tried out varying protocols. Certainly, these should likely be no more frequently than every other day to allow time for recovery from the high intensity of these workouts and full muscle glycogen repletion.”

This HIIT rule also applies to those who do not have diabetes, as true HIIT is a grueling form of exercise.

“It’s only detrimental if it causes lasting elevations in blood glucose that cannot be managed effectively or if such training results in injury (either acute or overuse),” continues Colberg.

“Most of the time, blood glucose rises during such sessions rather than decreasing, although blood glucose may drop more during the hours afterwards than it would normally following more moderate workouts.”

And why would blood sugar rise during high intensity interval training?
Because the body is under a tremendous demand for more energy expenditure.

The liver, in response to the significantly increased demand for energy, releases sugar into the bloodstream so that it can be shuttled (via insulin) to the muscle cells to fuel them.

In type 1 diabetes (10 percent of all diabetics), the insulin-receptor sites on muscle cells may be in perfect working order, but there’s no insulin or not enough of this hormone to transport sugar molecules to these sites.

In type 2 diabetes, the pancreas can be quite efficient at secreting plenty of insulin, and it does its job at transporting sugar to the muscle cells…

…except that the insulin-receptor sites either don’t work properly and thus can’t receive the sugar, and/or there’s just not enough of them. The result is high blood sugar.

In someone with diabetes, high blood sugar that directly stems from their condition can be compounded by even higher sugar as the liver – in response to HIIT – dumps out more sugar.

But HIIT, in and of itself, is not contraindicated by well-managed diabetes.

“My stance on HIIT is that it is not for everyone,” says Colberg. This includes non-diabetics, simply because high intensity interval training is pretty tough stuff – even when done on a stationary bike: sprint pedaling.

Colberg definitely endorses including some HIIT in one’s workout regimen if they’d like to, as it’s a scientifically-proven way to dramatically increase fitness and health, and it also uses up more glucose and glycogen (sugar stored in the muscles).

Whether diabetic or not, the person who’s new to high intensity interval training should first start out with sub-intense intervals rather than going all-out—even if their cardio machine of choice has pedals.

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.