Type 1 diabetes occurs when the body does not produce sufficient insulin to process the sugar (glucose) that the body uses for energy. Controlling blood glucose in diabetics can help prevent complications associated with the disease. Although exercise has been shown to benefit diabetics in other ways, previous studies assessing the connection between physical activity and blood glucose control have been controversial, according to background information in the article. Some have shown that glycosolated hemoglobin (HbA1c) levels, which reflect the individual's control of blood glucose levels over the previous two to three months, are reduced in diabetics who exercise regularly. However, other research has failed to make this link.
Antje Herbst, M.D., University of Bonn, Germany, and colleagues analyzed data from 19,143 patients (9,140 girls and 10,003 boys) age 3 to 20 years with type 1 diabetes. Physicians at 179 pediatric diabetes clinics in Germany and Austria entered data about each patient--including HbA1c levels, frequency of physical activity, age, weight and height--at every office visit between 1997 and 2004. The children were then placed into three groups based on how often they engaged in physical activity per week: zero times, one to two times, and three or more times. They were also placed in three age groups: 3 to 8.9 years, 9 to 14.9 years and 15 years or older. Body mass index (BMI) was calculated by dividing the weight in kilograms by the square of the height in meters, and then converted into a BMI z score based on the patients' gender, age and change in BMI over time.
Children in groups with less physical activity per week had higher HbA1c levels than those who engaged in more physical activity. When the researchers considered age, BMI z score, sex, physical activity, dosage of insulin taken by the patient to control blood glucose and how long the patient had type 1 diabetes, level of physical activity remained one of the most important factors associated with HbA1c level. In girls but not in boys, children who exercised more frequently had lower BMI z score, and in boys but not in girls less physical activity was associated with a higher insulin dosage. Physical activity had no influence on the number of patients who experienced severe hypoglycemia or hypoglycemia with loss of consciousness.
"Regular physical activity should be recommended in patients with type 1 diabetes mellitus," the authors conclude. "Regular physical activity results in better control of glycemia, including a lower HbA1c level and, in female patients, lower BMI. The risk for severe hypoglycemia or hypoglycemia with loss of consciousness or seizure is not elevated in pediatric patients with a high frequency of regular physical activity."