Exercise is one of the best ways to manage type 2 diabetes. It makes your cells use insulin better and can help keep your blood sugar in a healthy range. It also helps your cells take in that sugar.

But if you take insulin or certain diabetes medications, a workout can send your levels too low, a condition called hypoglycemia. Take these steps to keep it in a safe range.

Check It Out

Before. Test your sugar prior to a workout. It’s generally OK if it’s between 100 mg/dl and 250 mg/dl. If it’s below 100, you’ll need a snack. If you’re planning a long workout of 2 hours or more, don’t start until your reading is above 100.

If it’s higher than 250, check your urine for ketones. They’re produced when your body burns fat instead of sugar for fuel. Don’t exercise if you have them. Your blood sugar could go even higher and cause ketoacidosis, which might lead to a coma or death.

During. You won’t need to check during exercise unless you plan to work out for 2 hours or more. Then you should check it every hour.

If you have a low reading (70 mg/dl or lower), stop and have a snack -- about 15-20 grams of fast-acting carbs. Try a small piece of fruit, 1 cup of light yogurt, or 1 granola bar. Then check again in 15 minutes. If it isn’t back up over 100, do the same treatment and test again in another 15 minutes.

Yes, doing this can throw off your groove or mess with your time, if you’re competing. But if you keep going, your blood sugar will continue to fall and you might hit a dangerous low.

After. Check again when you’re done. That’ll show you how exercise affects your diabetes. It’ll also let you know if you need a snack right away (if it’s below 100 mg/dl) or if you can wait until your next meal or snack.

Your levels may drop for up to 24 hours after either a medium or tough workout, so test at your regular times, too.

Emergency Treatment

Keep a fast-acting sugar source within arm’s reach. These work well:

  • Glucose tablets or gels
  • Regular soda (not diet) or juice
  • Sports drinks
  • 1 tablespoon of sugar

Read the labels to see how much you need to eat or drink to get 15 grams of carbs.

Other Ways to Avoid Lows

A few tricks can help you prevent them when you exercise:

  • Don’t work out when your insulin will peak.
  • Finish up at least 2 hours before bedtime.
  • Skip alcohol before or right after you work out.
  • Stay out of hot tubs, saunas, and steam rooms directly after.
  • Get physical once or twice a day.

Are There Symptoms?

Not always. It can be easy to miss the warning signs of low blood sugar when you’re working out. Or you can mistake them for signs of a good workout: the same as sweating, fast heartbeat, feeling tired, and getting hungry.

If you notice anything unusual while you’re at it, check your sugar, especially if the symptoms don’t normally go with exercise, like:

  • Confusion or feeling delirious
  • Blurry or impaired vision
  • Tingling or numbness in your lips or tongue
  • Lack of coordination

A low might feel different for you during exercise than it does at night or if you don’t eat enough for the insulin you take at meals. When in doubt, check.

If You Keep Getting Exercise Lows

You’ll need to make a few changes. Talk to your doctor about options like:

  • Adjusting your insulin or medications (better if you’re trying to lose weight)
  • Eating more before you work out
  • Changing the kind of workout you do or how long you do it

WebMD Medical Reference

NEXT IN THE SERIES

From WebMD

More on Fitness and Diabetes