People with diabetes are advised to consult with their physician before starting or changing and exercise program. They are advised to monitor their glucose (blood sugar) before, during and after exercise. It is also important to drink enough water to avoid dehydration, which can worsen a glucose imbalance.

Those who use insulin are advised to pay particular attention to warning signs such as dizziness, headache and hunger (polyphagia), which may indicate that blood sugar has fallen too low (hypoglycemia). Left untreated, hypoglycemia can cause bodily damage and lead to serious diabetic complications, including insulin shock and diabetic coma.

Persons with type 1 diabetes in particular have sometimes been discouraged from taking part in vigorous activities because of the risk of exercise-induced hypoglycemia. Recent research, however, has shown that exercise is generally safe in people with type 1 diabetes and that it can reduce the risk of long-term complications such as heart disease.  Intermittent high-intensity types of exercise, such as soccer or other field sports, may be safer than continuous light exercise such as jogging, according to some research.

Recent research has found that children with type 1 diabetes may be more likely to experience overnight hypoglycemia after they exercise. Because exercise has many health benefits, parents are advised not to prohibit it but to consult with their child’s physician about how to prevent the anticipated drop in blood sugar, such as adjusting insulin or adding an evening snack on active days.

People using an insulin pump may be able to avoid postexercise hypoglycemia by turning off their pump during exercise, according to several studies. However, this strategy may cause hyperglycemia (excess glucose) and should not be tried without a physician’s recommendation.

Occasionally, exercise can increase the amount of glucose released into the bloodstream, causing hyperglycemia. People with diabetes should also pay attention to possible warning signs of hyperglycemia, such as weakness, thirst and fatigue. Like hypoglycemia, hyperglycemia can have serious medical consequences if left untreated.