Low blood sugar may be more likely with jogging

For active diabetics, moderate-intensity exercise, such as light continuous jogging or cycling, poses a greater risk of low blood sugar (Hypoglycemia) than intermittent high-intensity exercise representative of the activity patterns of team and field sports, such as soccer or hockey, a new study suggests.

"Our finding has implications for safe participation in exercise by individuals with Type 1 Diabetes," Dr. Kym J. Guelfi.

The observation is important, Guelfi and colleagues from the University of Western Australia note the journal Diabetes Care, "since many individuals with Type 1 Diabetes are discouraged from engaging in vigorous exercise because of a fear of exercise-induced hypoglycemia."

The researchers analyzed the response of blood sugar and hormones involved in the regulation of blood sugar on two separate occasions during which seven healthy young type 1 diabetics performed a moderate-intensity or intermittent high-intensity exercise program for 30 minutes.

Moderate-intensity exercise consisted of continuous exercise while high-intensity exercise entailed a combination of continuous exercise interspersed with sprints performed every 2 minutes to simulate the activity patterns of team sports.

The experiment was designed to reproduce a "real-life" situation in which insulin is injected and food is consumed as it normally would be before exercise, the team explains.

They found that both moderate-intensity and high-intensity exercise led to a decline in blood sugar levels, but the decline was greater with moderate-intensity than with high-intensity exercise, despite a higher heart rate and greater total work load with high-intensity exercise.

During the 60-minute recovery period after exercise, sugar levels remained higher after high-intensity exercise compared with after moderate-intensity exercise. Blood sugar levels remained stable during recovery from high-intensity exercise whereas they continued to decline after moderate-intensity exercise.

"Hopefully," Guelfi said, "this study will contribute to improved guidelines for individuals with type 1 diabetes to manage their (sugar) levels during and after exercise to avoid hypoglycemia. However, caution should be taken in generalizing these findings until further research has been conducted."

SOURCE: Diabetes Care, June 2005.