How Does Diabetes Affect Exercise?

Exercise has numerous benefits for all people with diabetes. If you have type 2 diabetes, exercise helps to maintain a healthy weight and reduce the risk for heart disease. It can also promote better blood sugar control and blood flow.

People with type 1 diabetes can also benefit from exercise. However, you should monitor your blood sugar levels closely. This is especially important if you take medications that raise your insulin production. If this is the case, exercise can lead to hypoglycemia or ketoacidosis. If you have type 2 diabetes but are not taking such medications, there’s very low risk of low blood sugars with exercise. Either way, exercise is beneficial as long as you take the appropriate precautions.

While you may not be motivated to exercise or you may be concerned about your blood sugar levels, don’t give up. You can find an exercise program that works for you. Your doctor can help you choose appropriate activities and set blood sugar targets to make sure you exercise safely.

Considerations When Exercising

If you haven’t exercised in some time and are planning to start something more aggressive than a walking program, talk to your doctor. This is especially important if you have any chronic complications or if you’ve had diabetes for more than 10 years.

Your doctor may recommend an exercise stress test prior to beginning an exercise program if you are over 40 years of age. This will ensure your heart is in good enough shape for you to safely exercise.

When you exercise and have diabetes, it’s important to be prepared. You should always wear a medical alert bracelet or other identification that lets people know you have diabetes, especially if you’re on medications that raise insulin levels. In this case, you should also have other precautionary items on-hand to help raise your blood sugar if needed. These items include:

  • fast-acting carbohydrates such as gels or fruit
  • glucose tablets
  • sports drinks that contain sugar, such as Gatorade or Powerade

While you should always drink plenty of fluids when working out, people with diabetes should be especially careful get enough fluids. Dehydration during exercise can adversely affect your blood sugar levels. Take care to drink at least 8 ounces of water before, during, and after your workout to stay hydrated.

Risks of Exercising with Diabetes

When you exercise, your body starts to use blood sugar as an energy source. Your body also becomes more sensitive to insulin in your system. This is beneficial overall. However, these two effects can cause your blood sugar to drop to low levels if you’re on medications that increase insulin production. For this reason, it’s important to monitor your blood sugar both before and after you exercise if you’re on these medications. Consult your doctor for ideal blood sugar levels before and after exercise.

Some people with diabetes may need to avoid strenuous exercise. This is true if you have some forms of diabetic retinopathy, eye disease, high blood pressure, or foot concerns. Strenuous exercise may also increase your risk of low blood sugar many hours after exercise. People who are on medications that put them at risk for low blood sugar should be careful to test blood sugars longer after strenuous exercise. Always talk with your doctor about the best approach given your unique health concerns.

Exercising outdoors can also affect your body’s response. For example, extreme fluctuations in temperature can affect your blood sugar levels.

What should you do if your blood sugar is too low or high before you intend to exercise? If blood sugar levels are high and you have type 1 diabetes, you can test for ketones, and avoid exercise if you are positive for ketones. If your blood sugar levels are low, you should eat something before you start exercise. Speak with your doctor to create a plan that works for you.

Monitoring Your Blood Sugar Before Exercise

You should check your blood sugar about 30 minutes prior to exercising to ensure it’s within a safe range. While your doctor may set individual goals with you, here are some general guidelines:

Less than 100 mg/dL (5.6 mmol/L)

If you’re on medications that increase insulin levels in the body, refrain from exercising until you have eaten a high-carbohydrate snack. This includes fruit, half a turkey sandwich, or crackers. You may wish to re-check your blood sugar before exercise to ensure it’s in the proper range.

Between 100 and 250 mg/dL (5.6 to 13.9 mmol/L)

This blood sugar range is acceptable when you begin exercising.

250 mg/dL (13.9 mmol/L) to 300 mg/dL (16.7 mmol/L)

This blood sugar level may indicate the presence of ketosis, so be sure to check for ketones. If they’re present, don’t exercise until your blood sugar levels have decreased. This is usually only an issue for people with type 1 diabetes.

300 mg/dL (16.7 mmol/L) or Higher

This level of hyperglycemia can quickly progress into ketosis. This can be worsened by exercise in people with type 1 diabetes who are insulin-deficient. People with type 2 diabetes rarely develop such a profound insulin deficiency. They don’t usually need to postpone exercise because of high blood glucose, so long as they’re feeling well and remember to stay hydrated.

Signs of Low Blood Sugar When Exercising

Recognizing hypoglycemia during exercise can be difficult. By nature, exercise puts stress on your body that can mimic low blood sugar. You can also experience unique symptoms, such as unusual visual changes, when your blood sugar gets low.

Examples of exercise-induced hypoglycemia symptoms in those with diabetes include:

  • irritability
  • sudden onset of fatigue
  • sweating excessively
  • tingling in your hands or tongue
  • trembling or shaky hands

If you experience these symptoms, test your blood sugar and rest for a moment. Eat or drink a fast-acting carbohydrate to help bring your blood sugar levels back up.

Recommended Exercises for People with Diabetes

The American Academy of Family Physicians recommends consulting with your doctor when determining the type of best exercise for you, given your overall state of health. A good place to start is some form of mild aerobic exercise, which challenges your lungs and heart to strengthen them. Some examples include walking, dancing, jogging, or taking an aerobics class.

However, if your feet have been damaged by diabetic neuropathy, you may wish to consider exercises that keep you off your feet. This will prevent more injury or damage. These exercises include riding a bicycle, rowing, or swimming. Always wear comfortable, well-fitting shoes coupled with breathable socks to avoid irritation.

Lastly, don’t think you have to be a marathon runner. Instead, try starting with aerobic exercise in increments of 5 to 10 minutes. Then work your way up to about 30 minutes of exercise most days of the week.