August 2003 � People over 40 who use aerobic exercise to prevent or control diabetes need not only regular, but frequent, exercise if they are to realize its potential benefits, according to a Mayo Clinic study published in the August 2003 issue of Diabetes, the Journal of the American Diabetes Association. Aerobic exercise is often prescribed to help prevent or control Type 2 diabetes.
"As people age, they typically experience a decline in insulin sensitivity, a key underlying factor that makes them more prone to becoming diabetic," says K. Sreekumaran Nair, M.D., a Mayo Clinic endocrinologist and the study's lead investigator.
The study found that middle-aged and older people don't sustain the increased insulin sensitivity that aerobic exercise produces, according to Dr. Nair. Younger people, on the other hand, were found to maintain higher insulin sensitivity even four days after their last workout.
"Previous studies by other researchers have shown that insulin sensitivity improves in older people if measured within a day of aerobic exercise," says Dr. Nair. "Our study focused on whether people of all ages retain the positive effects of a regular aerobic exercise program over a longer time."
With a decrease in insulin sensitivity, blood glucose levels increase. High blood glucose levels, typical in diabetes, can damage virtually every organ in the body. Increased insulin sensitivity helps regulate blood glucose, and prevent or reduce its potentially harmful effects.
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The study also examined whether a reduction in abdominal fat or changes in the body's ability to convert food to energy resulting from aerobic exercise might be related to changes in insulin sensitivity among those who exercise regularly.
For the study, 65 healthy, but mostly sedentary, men and women ages 21 to 87, engaged in a four-month aerobic exercise program. Training sessions grew in length and intensity over the period.
Researchers measured insulin sensitivity, abdominal fat and enzyme systems involved in cellular energy conversion at the beginning of the program -- and again three to four days after the last exercise session.
"The insulin sensitivity of younger people remained higher four days after exercising," says Dr. Nair. "But, no increase was recorded in middle-aged and older participants."
"The study found no close connections between increased insulin sensitivity in middle- and older-aged people and reduced abdominal fat or increased energy conversion," says Dr. Nair. Both younger and older participants had reduced abdominal fat and increased enzymes involved in cellular energy production when evaluated after the exercise program.
"The results may be helpful to prediabetic and diabetic patients and their health-care providers as they plan more effective exercise regimens," says Dr. Nair.
Source: Mayo Clinic
