It’s estimated that 88 million American adults have prediabetes – that's 1 in 3 adults! Every 17 seconds, an American is diagnosed with type 2 diabetes (T2DM), equating to 1.5 million new cases of diabetes a year, 90 to 95% of which is T2DM. Despite those stunning statistics, T2DM is NOT an inevitable consequence of prediabetes. Type 2 diabetes is preventable, and in some cases reversible. The results of the National Diabetes Prevention Program (NDPP), published in the New England Journal of Medicine in 2002, found that amongst patients with impaired glucose tolerance, a lifestyle program focused on healthy eating, regular aerobic physical activity and weight loss, reduced the cumulative incidence of T2DM by 58% compared to a usual care control group. Multiple studies since then have confirmed the findings of the original NDPP study. The Centers for Disease Control and Prevention (CDC), was charged to establish a national diabetes prevention program targeted at persons at high risk for diabetes.
The NDPP is now a 1-year program, which includes both didactic sessions and 1-on-1 counseling sessions. The program can be delivered in-person or virtually. It is covered by many insurance programs including Medicaid (in some states) and Medicare. The DPP is led by trained lifestyle coaches who teach and interact with participants over the course of the year to help them set and achieve goals. Weight loss is a significant predictor of T2DM prevention. Recently, the CDC updated its DPP standards, stating:
“Goals of the yearlong program should focus on moderate changes in both diet and physical activity to achieve one or more of the following outcomes: modest weight loss in the range of 5-7% of baseline body weight, a combination of a loss of 4% of baseline body weight and 150 minutes of physical activity per week on average, or a modest reduction in hemoglobin A1C (HbA1C) of .2%.” (1)
The combination option of a 4% weight loss and 150 minutes/week of physical activity on average was a change from the previous standards (as was the reduction in HbA1c goal). Several studies have demonstrated that physical activity level is both a predictor of prediabetes risk and an important component in T2DM prevention. The Finnish Diabetes Prevention Study found that an increase in moderate-to-vigorous and strenuous structured leisure time physical activity (LTPA) was associated with a large reduction in the risk of diabetes. “Moreover, an increase in the duration and intensity of walking for exercise and even lifestyle LTPA predicted a decrease in incident diabetes. Additionally, participants whose increase in walking for exercise was in the upper third were 59% less likely to develop diabetes than those whose change was in the lower third, independent of other factors. Moreover, a subjective increase in the pace of walking also decreased the likelihood of diabetes independently of time spent walking. A key message from a public health standpoint would be that at least 2.5 h/week of walking for exercise during follow-up seemed to decrease the risk of diabetes by 63–69%, largely independent of dietary factors and BMI.” (2) A 2015 meta-analysis found a strong inverse relationship between physical activity and risk of developing type 2 diabetes. (3) A 2021 publication examining the impact of physical activity on the original U.S. NDPP cohort found that physical activity was inversely related to incident diabetes in the entire cohort across the study. (4)
The CDCs NDPP program typically does not involve physical activity during class time. The didactic sessions include such topics as, “Jump Start Your Activity Plan,” “Move Those Muscles,” and “Find Time for Fitness.” Participants in the DPP must record and report their physical activity minutes per week. Physical activity is self-reported, no objective measures of activity or fitness are required. Desired intensity is defined as moderate or brisk. DPP lifestyle coaches are encouraged to review each individual’s reported physical activity at weekly or monthly follow-up sessions. (1) The updated NDPP standards provide an incentive for DPP programs to support participants in adopting a physically active lifestyle and may present opportunities for exercise professionals to improve program outcomes.
Given the strong evidence for physical activity in the prevention of type 2 diabetes, and the overwhelming prevalence of prediabetes amongst U.S. adults, it is incumbent upon all of us in medicine and fitness to promote regular physical activity as a key diabetes prevention strategy. The American College of Sports Medicine and Exercise is Medicine® should work closely with the CDC to support research, workforce development and clinical care that helps to “bend the incidence curve” for type 2 diabetes.