Wednesday, March 29, 2006

Exercise after a high-carb meal

The magnitude and duration of after-meal blood glucose elevation seem to be important risk factors for diabetes Type 2 and coronary heart disease.

Researchers investigated whether post-meal light physical activity might reduce this blood glucose increase.

  • Day 1 - Blood glucose was determined while resting, before meal, and each 15 min for the next 2 hours after ingesting a high carbohydrate meal of cornflakes.
  • Day 2 was similar to Day 1 but included light bicycling exercise for 30 min after finishing the meal.


In all trials, irrespective of age and training condition, light bicycling for 30 min after the carbohydrate meal blunted the rise in blood glucose. The results demonstrate an acute blood glucose reducing effect of light physical activity and of a magnitude similar to that obtained by hypoglycemic (diabetes medications or sulfonylureas) drugs, even after intake of a large dose of high glycemic food.

A great prescription: take a leisurely walk or ride a bike after a high carbohydrate meal to prevent a rise in blood glucose. (Glucose levels peak at 1 hour after the start of the meal and then return to preprandial levels within 2–3 h.)

In a study of patients with type 2 diabetes with secondary failure of sulfonylurea therapy, researchers showed that improvement of postprandial hyperglycemia, using insulin lispro (Humalog) at mealtime in combination with a sulfonylurea, not only reduced 2-h postprandial glucose excursions, but also reduced both fasting glucose and A1C levels from 9.0% to 7.1% Subjects also benefited from significantly decreased total cholesterol levels and improved HDL cholesterol concentrations.

A stunning result. Lower the after-meal glucose (by the use of insulin in this study) and you significantly improve A1C levels, currently the most important marker for diabetes control. If we could burn some carbohydrates with exercise after a high carbohydrate meal, perhaps we might remain non-diabetic, or if we are diabetic, cut medication dosage or even become non-diabetic.


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