Exercise and Diabetes

Exercise and Diabetes

Also called: Type 1 Diabetes & Exercise, Type 2 Diabetes & Exercise

Summary

Exercise is a cornerstone in the management of diabetes and the prevention of diabetic complications. It can help people avoid or control type 2 diabetes and gestational diabetes. For people with type 1 diabetes, exercise contributes to general health and reduces the risk of double diabetes.

Physical activity helps patients control glucose (blood sugar), blood pressure, weight and cholesterol. It assists in preventing a host of disorders including diseases of the heart, eyes, nerves and kidneys.

Patients are encouraged to meet with their physician before starting an exercise program. A medical history and physical examination 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 and stretching.

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

  • Monitoring glucose before and after exercise
  • Keeping water and carbohydrate-rich snacks handy
  • Wearing a medical identification tag
  • Heeding warning signs of low 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:

  • Insulin (a substance that regulates glucose)
  • Regular exercise
  • A nutritious diet

Type 1 diabetes, including a variation known as latent autoimmune diabetes of adulthood (LADA), is characterized by the body’s inability to produce insulin. Without this hormone, glucose 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:

  • Diabetic ketoacidosis and diabetic coma
  • Heart diseaseand stroke
  • Kidney disease (diabetic nephropathy)
  • Eye diseases including diabetic retinopathy, glaucoma and cataracts
  • Nerve damage (diabetic neuropathy)
  • Skin disorders, foot problems and amputation
  • Infections such as gingivitis and yeast infections
  • Sexual dysfunction

People with type 1 diabetes require regular insulin administration, which allows glucose to enter the cells from the bloodstream. Because exercise can affect glucose, patients who take insulin need to take additional precautions when exercising, particularly those who are prone to hypoglycemia or have hypoglycemia unawareness.

In addition to improving overall fitness, regular exercise as prescribed by a physician can help people with type 1 diabetes:

  • Control glucose, blood pressure and cholesterol
  • Enhance cardiovascular function
  • Manage weight
  • Prevent insulin resistance and double diabetes
  • Reduce the amount of insulin needed (as advised by a physician)
  • Prevent or delay complications of diabetes
  • Avoid unstable 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 prediabetes, in which glucose (blood sugar) is elevated but not yet high enough to be classified as diabetic.

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

  • Heart conditions and stroke
  • Kidney damage (diabetic nephropathy)
  • Nerve damage (diabetic neuropathy)
  • Blindness due to diabetic retinopathy, glaucoma or cataracts
  • Amputation due to ulcer or other foot problems
  • Diabetic coma
  • Sexual dysfunction
  • Dental problems

Prediabetes does not always progress to type 2 diabetes. Exercise, a nutritious diet and a normal body weight can delay and, in some cases, even prevent the onset of type 2 diabetes.

Exercise is a cornerstone of managing type 2 diabetes, along with:

  • Meal planning and nutrition counseling
  • Regular medical care
  • Antidiabetic agents (if necessary)
  • Insulin (if necessary)

A major factor in the development of type 2 diabetes is insulin resistance. The body produces an amount of insulin that should be adequate 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 glucose.

Some people are at higher risk for developing type 2 diabetes. Age, genetics, race and 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, benefits of exercise for people with type 2 diabetes include:

  • Controlling glucose, cholesterol and blood pressure
  • Fighting childhood obesity and adult obesity
  • Enhancing cardiovascular function
  • Reducing the need for medications, as determined by a physician
  • Preventing or delaying complications of diabetes

In addition, exercise helps prevent or control gestational diabetes, a form of diabetes that can develop in women during pregnancy. Exercise also plays a role in managing maturity-onset diabetes of the young, a genetic disorder that is sometimes considered a form of type 2 diabetes.

People are often advised to get 30 minutes of exercise at least five days a week. However, patients should consult their physician about what level of exertion and what amount and types of exercise are best for them.

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 can review a patient’s medical history and 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
  • Weight and body composition (comparison of body fat to lean tissue)
  • Glucose (blood sugar)
  • Feet
  • Eyes
  • 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. Patients may be advised to avoid exercises that increase the pressure in the blood vessels of the eyes, such as bouncing and weightlifting.
  • Heart disease or high blood pressure. Patients may be advised to avoid exercises that involve heavy exertion or keeping muscles contracted, such as weightlifting.
  • Foot problems or neurological conditions, such as diabetic neuropathy. Patients may be advised to avoid activities that could result in blisters on their feet, such as jogging.

Exercise precautions for people with diabetes

People with diabetes have different exercise requirements and considerations than nondiabetics. Individuals should consult their physician for specific recommendations. General precautions for people with diabetes include:

  • Test glucose (blood sugar) as recommended by the care team. For some patients, this means before, during and after exercise. The interaction of exercise and blood sugar is complex, and managing glucose during exercise can be tricky. Although regular exercise can help control glucose in most cases, physical activity can sometimes alter it too much. Exercise can lower blood glucose for hours afterwards, and more frequent glucose monitoring may be required. It is dangerous to exercise when glucose is lower than 100 milligrams per deciliter (mg/dL). Signs of hypoglycemia (low blood glucose) include shakiness, dizziness, headache, fatigue and hunger.

If blood glucose is too low before, during or after exercise, people with diabetes should follow their physician’s recommendations, which may entail one or more of the following:

  • Eating a small snack. A small snack containing 15 to 30 grams of carbohydrates is often ideal.
  • Taking sugar tablets or drinking a glass of fruit juice. In addition, people should drink enough water to avoid dehydration.
  • Adjusting 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 are advised not to 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.
  • Have identification. Carry identification and wear a medical ID tag, bracelet or necklace when exercising.
  • Avoid exercising right before bedtime because it might cause nocturnal hypoglycemia or contribute to the Somogyi effect.
  • 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 or synthetic moisture-wicking socks and correctly fitted athletic shoes. Proper foot care is important for all people with diabetes, but especially in cases of the nerve disease diabetic neuropathy, 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 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 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 glucose levels before, during and after each exercise session.
  • Consider carrying a glucagon kit. Glucagon is a hormone that acts contrary to insulin, raising the level of glucose in the bloodstream. It can be prescribed as a medication that is injected in case of severe hypoglycemia (insulin shock).

In addition, people taking insulin need to take precautions:

  • Consider the 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 insulin instead of rapid-acting insulin.
  • 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 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 makes it easier to anticipate insulin needs. Also, exercise during the morning can prevent nocturnal hypoglycemia.

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

Recent research indicates that holding the breath during resistance exercises such as weightlifting may increase the risk of glaucoma. Patients are advised to breath properly during exercise and get instruction if needed from an athletic trainer or other professional.

Exercise recommendations with diabetes

Most recommended exercise programs for people with diabetes will include:

  • Aerobic exercises (exercises that improve oxygen circulation). These activities involve the body’s large muscles and increase heart rate. People are often encouraged to engage in some form of aerobic activity for about 30 minutes a day at least five days a week. These activities may include:
    • Walking, hiking, jogging or 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.
  • Stretching. Following a light warmup, patients can perform stretching exercises for five to 10 minutes before and after physical activities to increase flexibility, reduce stress and prevent muscle damage and soreness.

The American Diabetes Association (ADA) in 2006 issued general guidelines advising people with type 2 diabetes to get at least 150 minutes of aerobic exercise a week at moderate intensity or at least 90 minutes a week at vigorous intensity. The exercise should take place over at least three days in the week, with no more than two exercise-free days in a row.

The recommendations also include three days a week of strengthening exercises targeting all major muscle groups, supervised regularly at first and occasionally thereafter by a qualified exercise specialist to reduce the risk of injury. The goal is to complete three sets using weight that cannot be lifted more than eight to 10 times.

The ADA advises people with prediabetes to get at least 150 minutes weekly of moderate to vigorous physical activity. The organization also plans to issue exercise recommendations for people with type 1 diabetes.

Questions for your doctor regarding exercise

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following  questions about exercise and diabetes:

  1. Can you clear me to start or alter an exercise program?
  2. What kind of exercises should I do? Are there any I should avoid?
  3. How much should I exercise? At what level should I start, and when can I lengthen my sessions?
  4. What effect can exercise have on my glucose?
  5. How will it affect my meal plan?
  6. What precautions should I take when exercising?
  7. In what other ways does exercise affect my diabetes?
  8. Do I need to test my blood sugar before and after exercise?
  9. Are there any other precautions I should take?
  10. What should I do if I feel possible symptoms of hypoglycemia?
  11. Do I need increased monitoring of glucose, blood pressure or anything else when I start exercising?
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