Topic Overview

You can safely exercise when you have diabetes. Here are some tips.

Before starting an exercise program

• Talk to your doctor about how and when to exercise. You may need to have a medical exam and tests (such as a treadmill test) before you begin. Also, some types of exercise can be harmful if you have complications from diabetes. Your doctor can tell you whether you need to avoid certain kinds of exercise.
• Choose a type of exercise that you like and that fits easily into your daily schedule. If you choose something you like, you will be more willing to continue the program.
• Plan to exercise at about the same time and for the same length of time each day to help keep your blood sugar levels in the same range. If you want to increase your exercise, increase the intensity or the duration in small amounts.
• Have someone with you when you exercise, if possible. You may need help if your blood sugar level drops below a target range.

Starting a program

Start slowly so that you don’t overdo it. Build up your exercise program bit by bit, and aim for at least 2½ hours a week of moderate activity. Or try to do vigorous activity for at least 1¼ hours a week.¹ It's fine to be active in blocks of 10 minutes or more throughout your day and week.

If you take certain pills used to treat type 2 diabetes or if you take insulin:²

• Check your blood sugar level before and right after you exercise until you can predict the effect of exercise on your blood sugar. Check your blood sugar more often if you greatly increase how long or how strenuously you exercise.
• Exercise changes the amount of glucose in your body. During vigorous exercise, the liver releases more stored glucose into the bloodstream. This raises blood sugar. When blood sugar is too high, it can lead to diabetic ketoacidosis. This can happen when you are very dehydrated. If you have Type 1 diabetes, make sure that your blood sugar is not too high before you begin to exercise:
  • If your blood sugar is over 250 milligrams per deciliter (mg/dL) 8 hours after you have eaten and you have ketones in your urine, do not exercise.
  • If your blood sugar is over 300 mg/dL and you do not have ketones in your urine, exercise with caution.
• Watch for signs of low blood sugar.
  • Avoid exercise when your blood sugar is too low (less than 70 mg/dL).
  • If your blood sugar is less than 100 mg/dL before you start exercising, eat a carbohydrate snack. This applies only to people who take insulin or medicine that lowers blood sugar. If your diabetes is controlled by diet and/or medicine that does not lower your blood sugar, you will not need to take a snack before exercising.
• Have some type of quick-sugar food with you when you exercise. You may have symptoms of low blood sugar while you exercise or up to 24 hours after you stop.
• Check with your doctor if you have been gradually increasing your exercise and have felt the symptoms of low blood sugar more than 2 or 3 times in one week. Your dose of medicine or insulin may need to be changed.

During exercise

• Exercise only after you have checked your blood sugar level.
• Wear shoes that fit well and polyester or blend (cotton-polyester) socks to keep your feet comfortable and to prevent blisters. Use silica gel or air midsoles in your shoes.
• Drink plenty of water before, during, and after you are active. This is very important when it’s hot out and when you do intense exercise.
• Wear medical identification at all times. You can get medical identification, such as a bracelet, from a pharmacy or on the Internet.
• Carry a quick-sugar food with you while you exercise.

For more information, see the topic Fitness: Getting and Staying Active.