For Diabetes, Exercise May Mean More Than Fitness

Exercise for type 2 diabetes patients may help with weight loss and blood sugar control, regardless of fitness gains

(RxWiki News) Even if exercise doesn't seem to be making you fitter, it could still be helping your health.

A new study from UT Southwestern Medical Center found that, even when exercise didn't appear to help diabetes patients get fit, it did seem to help their waistlines and their blood sugar control.

“What we observed is that exercise improves diabetes control regardless of improvement in exercise capacity,” said lead study author Dr. Jarett D. Berry, a professor at UT Southwestern, in a press release. “We were interested in the relationship between the change in cardiorespiratory fitness, or exercise capacity, and change in metabolic parameters."

Dr. Barry Sears, who was not involved with this study, said he thinks that weight loss is still an important marker for diabetes patients.

"Although the benefits on glycemic control of exercise were beneficial, those could only be noticed by clinical testing, not physical measurements (weight and waist circumference) that can be done at home," Dr. Sears, an expert in inflammatory nutrition and creator of the Zone diet, told dailyRx News. "I feel this means you have to have much greater calorie restriction in the patients to see meaningful results that maintain their motivation. This is in line with recent work that indicates exercise had little benefits relative to weight loss compared to calorie restriction, although the health benefits are clearly there."

Practically, there may be other challenges as well, Dr. Sears said.

"If you aren’t losing weight, it is unlikely you are going to maintain any enthusiasm for continuing to exercise even if your glycemic control is slightly improving," Dr. Sears said.

Type 2 diabetes is a metabolic disorder that occurs when body cells become resistant to insulin. Insulin is a hormone that regulates blood sugar. If the cells don’t respond to insulin, blood sugar can become so high that it causes damage to the cells and organs of the body.

Obesity — especially when fat centers around the waist — is common in type 2 diabetes. Diabetes patients who exercise may have better blood sugar control. They may also be able to lose weight.

Diabetes control is measured by a blood test called the hemoglobin A1c (HbA1c), which shows average blood sugar levels over time.

Most medical and exercise professionals measure fitness based on a patient's ability to take in oxygen. Exercise non-responders, however, cannot improve their fitness in this measure, no matter how much they exercise.

About 30 percent of people who exercise are non-responders. However, Dr. Berry and team found that other benefits may make the effort worthwhile for these patients, especially for people with diabetes.

Dr. Berry and colleagues used data from 202 patients in the Health Benefits of Aerobic and Resistance Training in Individuals With Type 2 Diabetes (HART-D) trial. They divided the patients into four groups.

The control group did not exercise. One group did only aerobic exercise. One did only resistance training (like weightlifting). One combined aerobic exercise and resistance training.

All three exercise groups showed improvements in HbA1c, indicating better blood sugar control. All the exercise groups decreased waist circumference and lost body fat.

Dr. Berry and team suggest that doctors should look at more parameters than just fitness, especially for people with type 2 diabetes. These researchers said blood sugar control, waist circumference and body fat should also be used to measure fitness.

“This finding suggests that our definition of ‘non-responder’ is too narrow," Dr. Berry said. "We need to broaden our understanding of what it means to respond to exercise training."

This study was published online in the June issue of the journal Diabetes Care.

The HART-D study was funded by a grant from the National Institutes of Health.

Co-author Dr. Darren K. McGuire received funds from GlaxoSmithKline, Takeda, Novo Nordisk, Janssen and Eli Lilly, among others. These companies make drugs and other products used to treat diabetes.

Review Date: 
June 18, 2015