Nutritional Pearls: Exercise Is More Effective Than Medication in Preventing Diabetes
A 51-year-old woman presents to your clinic with elevated fasting glucose concentrations. She has prediabetes and is wondering what she can do to prevent developing diabetes.
(Answer and discussion on next page)
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Answer: Exercise is an important tool in preventing diabetes.
In 1996, a team of researchers with funding from multiple US governmental research centers designed a study known as the Diabetes Prevention Program Research Group to compare the impact of an intensive lifestyle change regimen, medication, or placebo on the risk of developing diabetes.
The more than 30,200 participants averaged 51 years of age and had an average body mass index of 34 kg/m2, which is considered clinically obese. All participants had elevated fasting glucose concentrations indicating that they had prediabetes but not diabetes, and at least half of the participants were from "racial or ethnic minority groups."
The participants were randomly assigned to receive a twice-daily dose of metformin, a twice-daily dose of placebo, or were assigned to an intensive lifestyle counseling regimen that aimed to help the participants lose about 7% of their body weight and keep it off while also performing a minimum of 150 minutes of moderate-intensity exercise each week.
The study had originally aimed to last into 2002 but was terminated 1 year early because of its positive results. Those in the lifestyle arm of the study were 58% less likely to develop diabetes than those in the placebo group, while those taking metformin were 31% less likely to develop diabetes than those in the placebo group.
Today's research is an extension of that study.1 At the end of the original research, all participants were invited to participate in a version of the intensive lifestyle change regimen that had been so successful. Those who had been taking metformin continued taking the medication, while placebo administration was discontinued.
The researchers continued monitoring the nearly1800 participants who chose to continue to participate in the study, which lasted an average of 12 years for each participant.
Once again, the outcome measure was whether a participant developed diabetes as diagnosed by an oral glucose tolerance test.
On an annual basis, the researchers surveyed the participants’ levels of physical activity. A representative percentage of the participants consented to wear accelerometers for a 7-day period to measure not only their moderate or vigorous activity but also their light-intensity activity.
At the close of the study, the researchers assessed the risk of developing diabetes according to the participant's activity level, taking into account age, sex, weight at the start of the study, weight loss, and the usual amount of physical activity the participant engaged in at the start of the study.
For every additional 17 minutes of brisk daily walking, the participants saw a 6% reduction in their risk of developing diabetes. Those whose regular activity at the start of the study was less than the recommended 150 minutes per week but increased their activity to that level, actually reduced their risk of diabetes by 12%.
The lifestyle change program emphasized meeting the target of at least 150 minutes per week of moderate-intensity exercise, such as brisk walking, which is relatively equivalent to 300 minutes of light-intensity exercise, such as shopping or doing the dishes.
What is interesting is that of the 3 arms of the study––lifestyle, metformin, and placebo––those in the lifestyle arm did not exercise all that much more than the other 2 arms. The lifestyle arm averaged 20.7 minutes of moderate-intensity exercise and 363.5 minutes of light-intensity exercise per day, while the metformin and placebo groups averaged 19.6 and 353.3 minutes of light-intensity exercise, respectively. That is not a huge difference.
What This Means For You
Your take-home here should be that even if your patient has overweight, exercise is an important tool in preventing diabetes. As the researchers of this study put it, "[We] urge health care professionals to look beyond their high-risk patient's weight and consider his or her habitual [physical activity] levels when discussing lifestyle strategies to prevent progression to type 2 diabetes."
- Kriska AM, Rockette-Wagner B, Edelstein SL, et al; the DPP Research Group. The impact of physical activity on the prevention of type 2 diabetes: evidence and lessons learned from the diabetes prevention program, a long-standing clinical trial incorporating subjective and objective activity measures. Diabetes Care. 2021;44(1):43-49. https://doi.org/10.2337/dc20-1129