Type 2 Diabetic Patients and Exercise: How Much of What Kind?
Our mental picture of the usual “adult-onset” diabetic encompasses a sedentary lifestyle, a fondness for simple carbohydrates and all things sweet, and a body habitus that can range from overweight to morbidly obese. That picture fails to consider a notable minority of these patients, perhaps lost in the shadows or out of focus. Among all the people in the United States with type 2 diabetes, and there are 30,000,000 of them, 20 percent or 6,000,000 are, surprisingly, of normal weight.
Besides spoiling our perfect picture of the type 2 diabetic population, this subgroup also falls victim to the obesity paradox in that they have a greater risk of mortality than obese diabetics.
These facts have led Clinical Professor Latha Palaniappan, MD, MS (General Medical Disciplines), to design a randomized clinical trial among Stanford patients with type 2 diabetes and normal weight to see which type of exercise is best for them. Patients will undergo nine months of structured exercise, either aerobic or weight training or combined aerobic and weight training.
Palaniappan explains the scientific thinking behind the trial, which is funded by the National Institute of Diabetes and Digestive and Kidney Diseases: “Normal weight diabetics may be more insulin resistant than other diabetics. We think it might be due to sarcopenia, lack of muscle mass. When we eat, 80 percent of our glucose gets put in our muscles through GLUT4 receptors. If we don’t have enough muscle, we don’t have enough GLUT4 receptors to get the glucose out of the blood and into the muscle.
“The Strength Training Regimen for Normal Weight Diabetics (STRONG D) study is testing whether strength training, aerobic training, or a combination might be best for type 2 diabetics who have normal weight.” This study will be done in collaboration with the YMCA.
The outcome will be improvement in diabetes control as measured by the percent reduction in hemoglobin A1c. Patients are currently enrolling in STRONG D.
Stanford’s IMPACT Study
Palaniappan has a second study underway in patients with type 2 diabetes, and this one arose out of frustration over the lack of insurance coverage for supervised physical activity in patients with type 2 diabetes. Unlike those patients she refers to nutritionists within the medical system, the cost of whose interactions is covered by health insurance, “with physical activity I don’t have a resource for them. All I can do is tell them to get a pair of shoes and walk or go to the YMCA. We don’t have an implicit endorsement of physical activity for diabetics in the clinical setting, although we do that with other diseases.
“For instance, when you have a heart attack you are sent for cardiac rehabilitation and supervised physical activity three times a week,” she says. “There are lots of good studies that show that cardiac rehabilitation improves mortality and other outcomes. We want to see if a similar supervised exercise program is clinically effective and cost effective for patients with type 2 diabetes mellitus.”
This study is called IMPACT, which stands for the Initiate and Maintain Physical Activity in Clinics Trial, and it is currently enrolling. It is being done in collaboration with HeartFit For Life, a well-established cardiac rehabilitation program.
With New Year’s resolutions on both patients’ and physicians’ minds, this is a good time to suggest that patients enroll in a physical activity trial.
Colleagues interested in potential ancillary studies in the STRONG D and IMPACT patient populations are welcome to contact Dr. Palaniappan. In collaboration with Drs. Mike Snyder and Joseph Wu, biobanking is planned for the participants. Specifically, she says, “We are biobanking these patients before and after exercise, so we will have wonderful data for people who are interested in studying the molecular effects of exercise.”