Exercise Reduces Diabetes by Reducing Insulin Resistance

It has been shown numerous times that exercise may prevent certain diseases such as heart disease and diabetes, although the exact mechanism of this effect is often disputed. This study found that one of these mechanisms is that physical activity causes a reduction in insulin resistance.

• The study included 5159 men aged 40 to 59 years with no history of coronary heart disease, type 2 diabetes, or stroke.
  
• During an average follow-up period of 16.8 years, there were 616 cases of major coronary heart disease events (fatal and nonfatal) and 196 incident cases of type 2 diabetes.
  
• Physical activity was inversely related to coronary heart disease rates, with the lowest rates in the men undertaking moderate physical activity and with no further benefit thereafter.
  
• For type 2 diabetes, risk decreased progressively with increasing levels of physical activity.
  
• Physical activity was associated with serum insulin level and with factors associated with insulin, ie, heart rate, hyperuricemia (elevated uric acid in the urine), diastolic blood pressure, and high-density lipoprotein cholesterol level, and with -glutamyltransferase level, a possible marker of insulin resistance in the liver.

The authors maintain that insulin resistance definitely plays an important role in the development of diabetes, although they were not able to come to the same conclusion in regards to heart disease. They feel that the majority of the risk reduction for heart disease induced by exercise must be obtained through a different mechanism.