High Intensity Exercise Improves Glucose Control In Type-2 Diabetics

One of the most effective ways for type-2 diabetics to improve glucose control is through endurance training. Unfortunately the time commitment required for this type of exercise is often too much for diabetics. Interestingly, a new study, published last month in the journal Diabetes, Obesity and Metabolism has found that short duration high intensity physical activity may be just as effective as longer duration endurance exercise in improving glycemic control in type-2 diabetic patients.

The study, led by Professor Martin Gibala of the Department of Kinesiology, McMaster University, Canada, involved seven adults with type-2 diabetes who underwent a session of high intensity physical exercise involving 10 sixty second cycling sprints with a target heart rate of 90% maximum alternating with 1 minute rest periods. The researchers compared the 24-hour glucose levels of the participants with their levels on a control day that involving no physical exercise.

The authors found significant decreased in overall blood glucose levels as well as post-prandial glucose levels (glucose levels immediately following a meal). The amount of time spent with glucose levels above 10 mmol/l decreased from an average of 15.2% on the control day to 4.5% on the exercise day. Post-prandial glucose levels, as measured by the area under the 3-hour glucose response curve following meal times, decreased by 36%.

Professor Gibala has previously conducted studies on high intensity exercise that have produced similar results. A 2011 study published in the Journal of Applied Physiology, found that 6 30-minute high intensity sessions performed over two weeks decreased glucose levels by 13% and improved skeletal muscle mitochondrial capacity – a measure of metabolic health.

Skeletal muscle is the major contributor to post-prandial glucose clearance however it is generally impaired in type-2 diabetics. Insulin and physical exertion both increase glucose uptake by the skeletal muscle. Studies have also shown that repeat physical exercise increases the glucose transport capacity of skeletal muscle.

Most type-1 diabetics, and some type-2 diabetics who require insulin may actually experience slight increases in blood sugar levels immediately after high intensity exercise due to an increase in the levels of counter-regulatory glucose hormones which are released to prevent hypoglycaemia (low blood sugar). This increase in blood sugar levels usually lasts just 1-2 hours while the benefits of high intensity exercise, in terms of improved glucose control, last 24-48 hours.

High intensity physical exercise is not normally recommended for patients with pre-existing heart disease, a BMI greater than 35, or a history of exercise induced syncope.

The American Diabetes Association recommends that diabetics spend 150 minutes a week performing moderate to vigorous aerobic exercise.