Exercising Safely with Type 1 Diabetes

Physical activity is associated with many health benefits and is an important part of any healthy lifestyle. For individuals with type 1 diabetes, exercise provides additional benefits—and its own set of risks. In this article, we'll explore the health benefits, potential risks, and general guidelines that people with type 1 diabetes should keep in mind when starting and maintaining an exercise program. *Please note that the information in this article is intended to enhance discussion with your physician. It is NOT a substitute for talking to your health care provider before you begin an exercise program, or if you experience any problems in connection with exercising.

How Exercise Benefits People with Type 1 Diabetes
In addition to all of the usual health benefits of exercise, such as weight control, stress reduction, improved muscular strength and flexibility, and reduced bone loss, a sound exercise program can also help people with type 1 diabetes better use insulin and reduce their risk of heart disease.

Exercising on a regular basis can improve the sensitivity and number of insulin receptors in the body, according to the American Council on Exercise; this in turn helps train your muscles to use insulin better. These improvements in insulin utilization may lead to a decrease in insulin requirements for some individuals, but because people with type 1 diabetes are unable to make any insulin, no amount of exercise will ever eliminate the need for insulin injections.

People with type 1 diabetes are at an increased risk for heart attack, stroke, and other cardiovascular diseases, but regular exercise can help reduce these risks. Consistent physical activity has been proven to raise HDL (good) cholesterol, lower LDL (bad) cholesterol, and reduce triglycerides in the bloodstream. Physical activity also improves blood flow, increases your heart’s pumping power, and reduces blood pressure.

It is worth noting that exercise has not consistently been shown to improve blood glucose control in people with type 1 diabetes. However, given its other numerous benefits, exercise is still an important part of living well with type 1 diabetes.

Exercise Risks and How to Avoid Them
Exercise can be risky to anyone who hasn't been physically active in awhile, but there are several potential risks that people with type 1 diabetes must carefully consider prior to beginning an exercise program. You should have a lengthy discussion with your health care provider to better understand how exercise influences blood glucose, and how to avoid potential problems, minimize risks, and recognize when you need to get additional information or medical care. Here are four of the most common problems that you must consider and address when planning your exercise program.

Exercise Risk #1: Hypoglycemia
Exercise typically reduces blood sugar levels—especially when combined with insulin injections. When blood sugar drops too low, a complication known as hypoglycemia (low blood sugar) occurs. Hypoglycemia can happen during exercise, right after exercise, or even up to 24 hours after you work out. Symptoms of hypoglycemia can be mild and gradual, but it is more common for them to occur quickly. In rare cases, individuals may not experience any symptoms of hypoglycemia at all. By paying close attention to how you’re feeling, and by knowing how to recognize and treat symptoms of low blood sugar correctly, you can prevent problems before they put you at risk of injury.

Because the risk of hypoglycemia increases with exercise, it is important to plan your new exercise regimen carefully (more on that below). Here are some ways people with type 1 diabetes can reduce their risk of hypoglycemia during and after exercise.
  • Always check your blood sugar before, during, and after exercise.
  • Talk with your doctor about whether adjusting your insulin doses (or basal infusion rates, if you use an insulin pump) around planned exercise is right for you. Adjusting insulin doses around planned exercise can minimize your need for extra snacks prior to exercise, thereby helping you manage your weight.
  • NEVER adjust these doses under any circumstances, without consulting your physician first.
  • Eat 15-30 grams of carbohydrates 30 minutes prior to any physical activity that is not part of your regular fitness plan for diabetes management. Talk to your doctor or diabetes educator for specific guidelines.
  • In order to ensure that insulin is not absorbed too quickly, increasing the risk of hypoglycemia, it is best to avoid giving any insulin injections prior to exercise into areas of the body that will be worked during exercise (upper thighs and tricep region of the upper arms).
  • Do not skip planned meals prior to exercise or go too long without eating.
  • Carry an easy-to-consume source of fast-acting sugar (such as juice, hard candy, or glucose tablets) when you exercise. You will use this to treat hypoglycemia should it occur.
  • Drink plenty of water before and during exercise. Dehydration can affect blood glucose levels.
  • Avoid exercising in extreme weather conditions.
  • In special cases, athletes and people who have successfully adopted a long-term fitness plans will need specific self-management instructions from their physicians.
Exercise Risk #2: Poor Blood Sugar Control
In some cases, exercise can cause blood sugar levels to rise, resulting in hyperglycemia. If your blood glucose levels are not in your target range, talk to your doctor before beginning an exercise program. To prevent exercise-related blood sugar problems:
  • Do NOT exercise if your blood glucose is above 250 mg/dL and you have ketones in your urine. Call your doctor’s office for additional advice.
  • Check your glucose level before, during, and after exercise, to see how your exercise has affected it. Share this information with your doctor.
Exercise Risk #3: Diabetic Retinopathy
If you have this condition (damaged blood vessels in the retina of the eye), exercise could damage your eyesight. Strenuous activities could lead to bleeding or retinal detachment, so you may need to avoid certain activities, such as weight lifting or jogging. Ask your doctor to recommend appropriate exercise activities for you.

Exercise Risk #4: Reduced Sensation or Pain in the Extremities
Because diabetes can cause nerve damage (neuropathy) and interfere with blood circulation, many people with diabetes can lose all or part of the sensation in their feet. To prevent exercise-related foot problems:
  • Check your feet for cuts, blisters, or signs of infection on a regular basis.
  • Wear good, properly-fitting shoes with ample cushioning and support
  • Wear synthetic, wool or cotton-blend socks (not 100% cotton) that minimize moisture problems.
If you experience pain in your legs (or other extremities) at anytime during or after your exercise routine, contact your doctor right away. Exercise-induced pain can be a symptom of one or more diabetes-related complications that require medical attention. If numbness or pain becomes constant or severe, talk to your doctor about alternate forms of exercise that may be appropriate.

Recap: Quick Exercise Checklist for People with Diabetes
There’s no doubt about it—consistent, moderate exercise is one of the most important and effective weapons you can use to affect your overall health. To keep yourself safe, follow this checklist:
  • Talk to your doctor about the right exercises for you.
  • Always check your blood sugar level before, during, and after exercising.
  • Always wear diabetes identification. Every person with diabetes should wear a comfortable necklace or bracelet that states he or she has diabetes.
  • Ideally, work out with a partner that is knowledgeable about your medical condition.
  • Check your feet for blisters or sores before and after exercising.
  • Wear proper shoes and socks.
  • Warm up before each exercise session, and cool down and stretch afterwards.
  • Drink plenty of fluids before, during, and after exercising.
  • Bring a fast-acting carbohydrate snack in case you experience symptoms of hypoglycemia.
  • Report any recurring exercise-related pain in your legs or extremities to your doctor right away.
American Dietetic Association. Medical Management of Type 1 Diabetes, Fifth Edition. 2008. American Diabetes Association.
Exercise and Type 1 Diabetes, from the American Council on Exercise (ACE)
Take Charge of Your Diabetes, from the CDC's Diabetes Public Health Resource
What I Need to Know about Physical Activity & Diabetes, from the National Diabetes Information Clearinghouse.

For more specific information or help, talk to your health care provider. The American Diabetes Association's National Call Center also offers live advice from 8:30 a.m. to 8 p.m. EST, Monday through Friday at 1-800-DIABETES or 1-800-342-2383.