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.