Exercise and Diabetes

Exercise is a cornerstone in the management of diabetes and the prevention of diabetic complications. For people with type 1 diabetes, exercise, along with a balanced diet and insulin injections, plays a key role in maintaining good health. Exercise is also key to preventing or delaying the onset of type 2 diabetes, as well as controlling the condition if it occurs.

Type 1 diabetes is characterized by the body’s inability to produce enough insulin, a hormone that regulates glucose (blood sugar). Poorly controlled glucose can lead to numerous medical complications, including heart disease, kidney disease, blindness and amputation. Exercising regularly (and according to a physician's instructions) helps people with type 1 diabetes manage their blood glucose, lose weight and improve cardiovascular health.

Type 2 diabetes is characterized by the body’s inability to use insulin effectively. Many people with type 2 diabetes can manage their condition through diet and exercise alone. Additionally, consistent physical activity can improve cardiovascular functioning and promote weight loss, both of which are essential in the management of type 2 diabetes.

All people with diabetes are encouraged to meet with their physician before starting an exercise program. The physician will conduct a physical examination to help determine which types of activities are safest and most appropriate. Most recommended exercise programs for people with diabetes will include aerobic activity, strength training (weight–bearing activity) and stretching.

People with diabetes have different exercise considerations than non diabetics. These include:

  • Testing blood glucose before and after exercise
  • Keeping water and carbohydrate–rich snacks handy
  • Wearing a medical identification tag
  • Heeding warning signs of low blood glucose (hypoglycemia)
  • Adjusting insulin (if used) before and after workouts
  • Taking care of the feet before, during and after exercise

About Type 1 Diabetes and Exercise
There are three essential components in managing type 1 diabetes. They are:

  • Regular exercise
  • Proper diet and nutrition
  • Insulin injections (a substance that regulates glucose)

Type 1 diabetes is characterized by the body’s inability to produce insulin. Without this hormone, glucose (blood sugar) builds up in the bloodstream instead of entering the cells. The body is unable to use this glucose for energy. Poorly controlled glucose can lead to numerous medical complications, including:

  • Heart disease
  • Kidney disease (diabetic nephropathy)
  • Eye disease (including diabetic retinopathy)
  • Nerve damage (diabetic neuropathy)
  • Amputation

People with type 1 diabetes require daily insulin injections, which allow glucose to escape from the bloodstream and enter the cells. Because exercise can affect blood glucose levels, people with diabetes using insulin need to take additional precautions when exercising.

In addition to improving overall fitness, 30 minutes of exercise at least five days a week can help people with type 1 diabetes:

  • Control blood glucose
  • Improve cardiovascular function
  • Reduce cholesterol
  • Control blood pressure
  • Manage weight
  • Reduce the amount of insulin needed
  • Prevent or delay complications of diabetes

About Type 2 Diabetes and Exercise

Consistent, moderate exercise plays an important role in the prevention and management of type 2 diabetes. Almost all people who eventually develop type 2 diabetes first have a condition known as pre-diabetes, a condition in which glucose (blood sugar) levels are elevated but not yet high enough to be classified as diabetic.

Uncontrolled or greatly elevated glucose (hyperglycemia) can trigger a variety of complications in people with type 2 diabetes, including:

  • Kidney damage (nephropathy)
  • Nerve damage (neuropathy)
  • Blindness
  • Dental problems

A diagnosis of pre-diabetes does not always progress to a diagnosis of type 2 diabetes. Exercise, a healthy diet and a healthy body weight can delay and, in some cases, even prevent the onset of type 2 diabetes.
Exercise is one of the four cornerstones of diabetes management, along with:

  • Proper diet and nutrition
  • Proper use of medications (if necessary)
  • Insulin injections (if necessary)

A major factor in the development of type 2 diabetes is insulin resistance. The body produces enough insulin to meet its needs, but is unable to detect its presence or use it properly. When the body cannot efficiently use insulin, it cannot regulate levels of blood glucose.

Some people are at higher risk for developing type 2 diabetes. Age, genetics, ethnicity, weight and other factors all play a role in the likelihood of developing resistance to insulin. Exercise can delay or prevent the onset of diabetes because it increases the body's sensitivity to insulin, which allows the body to use the hormone more effectively.

People who have type 2 diabetes who take certain oral antidiabetic medications, including sulfonylureas (drugs that increase insulin production of the pancreas) and meglitinides (drugs that lower the circulating levels of blood glucose), should pay particular attention to their glucose levels during exercise. These individuals are at increased risk for developing hypoglycemia (low blood sugar), which can be life–threatening.

In addition to improving overall fitness, 30 minutes of exercise at least five days a week can help people with type 2 diabetes:

  • Control blood glucose
  • Improve cardiovascular function
  • Reduce cholesterol
  • Control blood pressure
  • Manage weight
  • Reduce or eliminate the need for medications, as determined by a physician
  • Prevent or delay complications of diabetes

Pre-Workout Checkup

Everyone should consult a physician prior to beginning an exercise program, but this is even more important for people with diabetes. The physician will conduct a physical examination to help determine which activities are safest and most appropriate. The physician will check the patient’s:

  • Heart
  • Blood pressure
  • Cholesterol
  • Body composition (comparison of body fat to lean tissue)
  • Eyes
  • Feet
  • Glucose (blood sugar)
  • Additional health concerns

If the patient is over age 35, the physician is more likely to recommend a stress test (a graded test that measures a patient’s oxygen intake and heart rate during strenuous physical activity). Patients who require medication may be advised to plan workouts around their medication schedule, and individuals who take insulin may be instructed to adjust their dosages before and after exercising.

Sometimes people with diabetes have complications that can be aggravated by certain types of exercise. Patients with certain diabetic conditions may be instructed to avoid particular activities. These complications include:

  • Eye conditions, such as diabetic retinopathy (a condition in which the small blood vessels in the retina leak fluid and become swollen). Patients may be advised to avoid exercises that increase the pressure in the blood vessels of the eyes, such as bouncing and weightlifting.
  • Neurological conditions, such as diabetic neuropathy (nerve damage caused by diabetes). Patients may be advised to avoid activities that could result in blisters on their feet, such as jogging.
  • Heart disease or high blood pressure (a condition that occurs when the tension of the blood in the artery walls is greater than normal). Patients may be advised to avoid exercises that involve keeping muscles contracted, such as weightlifting.

Exercise precautions for people with Diabetes

People with diabetes have different exercise requirements and considerations than nondiabetics. General precautions for people with diabetes include:

  • Test glucose (blood sugar) levels before and after exercise. This is important for people with type 1 and type 2 diabetes. Managing blood glucose during exercise can be tricky. Although regular exercise can help control glucose in most cases, physical activity can sometimes raise or lower it too much. Exercise can lower blood glucose levels for hours afterwards, and more frequent glucose tests may be required. It is dangerous to exercise when glucose is lower than 100 mg/dL. Signs of hypoglycemia (low blood glucose) include dizziness, headache, fatigue and hunger.

    If blood glucose is too low before, during or after exercise, people with diabetes should do one or more of the following:
    • Eat a small snack. A small snack containing 15 to 30 grams of carbohydrates is ideal.
    • Drink a glass of fruit juice. In addition, people should drink enough water before, during and after exercise.
    • Adjust medication prior to exercising.
  • Avoid exercise when insulin is functioning at peak levels or blood glucose exceeds 300 mg/dL and ketones (chemicals produced when the body relies on stored fat instead of glucose for energy) are present in urine. Consult a physician if blood glucose remains at elevated levels for a prolonged period. People with type 1 diabetes should never exercise if blood glucose exceeds 300 – even in instances where no ketones are present – because it increases the risk of developing diabetic ketoacidosis, a life–threatening condition that combines extremely high glucose and a severe lack of insulin. Contact the physician immediately if this occurs.
  • Keep water, glucose tablets or gel and snacks handy during exercise. Drink a sufficient amount of water before, during and after a workout to avoid dehydration, and eat a carbohydrate–rich snack (such as raisins) if glucose levels begin to plummet.
  • Identification. Always carry identification and wear a medical identification tag, bracelet or necklace when exercising.
  • Avoid exercising right before bedtime because it might cause hypoglycemia during the night.
  • Exercise with a friend. If possible, make sure that exercise partners or workers at any athletic facility are familiar with the warning signs of hypoglycemia.
  • Wear cotton socks and well–fitting athletic shoes. Proper foot care is important for all people with diabetes, but especially in cases of diabetic neuropathy (a nerve disorder caused by diabetes), which can cause feet to lose sensation.
  • Pay attention to warning signs. Dizziness, faintness, shortness of breath, nausea, heart palpitations, tightness in the chest and pain in the jaw or arm may indicate problems. People with diabetes experiencing any of these should immediately halt exercise and check their blood glucose.
  • Avoid exercising outside during extremes of hot or cold weather.
  • Do not drink alcohol before, during or after exercise because of the effects on blood glucose.
  • Do not skip a meal before exercising.
  • Track progress. Keep an exercise diary that includes a list of short– and long–term goals and notes about blood glucose levels before, during and after each exercise session.

In addition, people with diabetes taking insulin need to take the following precautions:

  • Consider their insulin schedule. Patients should speak with their physician about the type, frequency and intensity of recommended exercises, as well as how insulin injections may affect their exercise plan. For instance, the physician may suggest waiting one to three hours after an injection to begin a particular exercise to prevent hypoglycemia. The physician may also recommend switching to a different type of insulin before physical activities, such as regular instead of rapid-acting.
  • Consider insulin injection site. Avoid injecting insulin directly into a part of the body that will be used during exercise because the insulin will be absorbed more quickly in that region. This could lead to elevated blood glucose (hyperglycemia).
  • Time workouts. Try to exercise at the same time each day, preferably one to two hours after a meal. A consistent exercise schedule allows people with diabetes taking insulin to better anticipate their daily insulin needs. Also, people with diabetes should exercise during the morning whenever possible. Evening exercise can trigger hypoglycemia during the night.

In addition, people with diabetes and certain other conditions may be advised to limit certain activities

Exercise Recommendations with Diabetes

Most recommended exercise programs for people with diabetes (type 1 and type 2) will include:

  • Aerobic exercises (exercises that improve oxygen circulation). These activities involve the body’s large muscles and increase heart rate. Most patients will be encouraged to engage in some form of aerobic activity for about 30 minutes a day at least five days a week. These may include:
    • Walking
    • Hiking
    • Jogging/running
    • Swimming
    • Bicycling
    • Rowing
    • Skating
    • Dancing
  • Strength training exercises (resistance exercises that rely on the use of free weights, elastic bands or weight machines). When performed at least three times a week, strength training exercises can help to build muscle, increase metabolism and reduce excess body fat in people with type 2 diabetes.
  • Stretching exercises. Patients should perform stretching exercises for five to 10 minutes before and after all physical activities to increase flexibility, reduce stress and prevent muscle damage and soreness

Before beginning any exercise program, please consult with the medical professionals at Diabetes and Lipid Clinic of Alaska.

The information on this Web page is provided for educational purposes. You understand and agree that this information is not intended to be, and should not be used as, a substitute for medical treatment by a health care professional. You agree that Diabetes and Lipid Clinic of Alaska is not making a diagnosis of your condition or a recommendation about the course of treatment for your particular circumstances through the use of this Web page. You agree to be solely responsible for your use of information contained on this Web page

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