Supervised exercise may prevent diabetes over ten years: JAMA

Lifestyle intervention comprising regular exercise and diet has proven to be effective for type 2 diabetes prevention in people at high risk. However, the sole effect of vigorous and moderate exercise on diabetes prevention has not been studied well. Therefore, Ying Chen from Fudan University in Shanghai, China, and colleagues assessed the long-term effect of moderate and vigorous exercise on incident diabetes over a follow-up of 10 years after a 12-month exercise intervention.

According to the researchers, the exercise programs during the 1-year intervention were strictly supervised and coached, and all participants were told not to change their diet.

Following the exercise intervention, all participants were encouraged to stick to a healthy lifestyle and involve in moderate-intensity aerobic exercise. 94.5% of the 220 participants completed the 1-year exercise program, and 81.4% remained for the 10-year follow-up. Among the participants, the mean age was 54, and 32.3% were men. The average baseline weight was 72 kg (159 lb).

Incident diabetes was defined as an HbA1c of 6.5% or more, a fasting plasma glucose level of 126 mg/dL or higher, and the use of anti-diabetic medication.

Key findings of the study include:

• The diabetes risk was reduced by 53% in the moderate exercise group (relative risk [RR] 0.47) and 49% in the vigorous exercise group (RR 0.51) compared with adults who did not exercise.
• Over ten years, the cumulative incidence of type 2 diabetes was 1.9 per 100 person-years in the moderate group, 2.1 per 100 person-years in the vigorous group, and 4.1 per 100 person-years in the non-exercise group.
• The authors did not observe any significant changes in body weight between groups at either follow-up of 2-year or ten years; in the exercise groups, body weight was slightly lower than the non-exercisers. This also holds for fasting plasma glucose levels.
• For both exercise groups, the researchers observed a remarkably lower waist circumference -- 96.6 cm for the vigorous group and 96.8 cm for the moderate group compared to 101.4 cm for non-exercisers at ten years was seen.
• At ten years, exercisers saw significantly lower HbA1c levels (5.96 for vigorous and 5.95 for moderate versus 6.25 for no exercise).
• All groups had comparable levels of leisure time physical activity at baseline. Still, by the end of the program, both exercise groups just about doubled their median time (31 metabolic equivalent hours/week for vigorous, 31 for moderate, and 15.4 for non-exercisers).
• While the exercise groups never entirely dropped back down to baseline levels of leisure time physical activity, in the following years, their levels did taper off a bit, to the point where they were no longer significantly different compared to the non-exercisers.
• Of the three groups, the researchers diagnosed 30 new cases of type 2 diabetes in the non-exercise group, 15 in the vigorous exercise group, and 14 in the moderate exercise group.

"Our findings support physical exercise as an effective scheme for obesity management to delay type 2 diabetes progression, and vigorous and moderate aerobic exercise programs could be implemented for type 2 diabetes prevention in obese people," the researchers conclude.

Reference:

Chen Y, Chen Z, Pan L, et al. Effect of Moderate and Vigorous Aerobic Exercise on Incident Diabetes in Adults With Obesity: A 10-Year Follow-up of a Randomized Clinical Trial. JAMA Intern Med. Published online January 30, 2023. doi:10.1001/jamainternmed.2022.6291