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High-intensity training improves beta-cell function in sedentary adults with type 2 diabetes
Sedentary adults with type 2 diabetes who completed a 6-week functional, high-intensity training program saw improvement in beta-cell function and a reduction in fat mass, according to findings from a pilot, proof-of-principle study.
“Here we show that exercise at high intensity for as little as 10 to 20 minutes per day, 3 days per week for 6 weeks improves beta-cell function in adults with type 2 diabetes,” John P. Kirwan, PhD, of the department of pathobiology at the Cleveland Clinic Lerner Research Institute, and colleagues wrote. “The fasting proinsulin/insulin ratio, representing the processing inefficiency of insulin within the beta cell, was also significantly reduced following the intervention, providing further evidence for improved beta-cell function.”
Kirwan and colleagues analyzed data from 12 adults with type 2 diabetes recruited from the Cleveland metropolitan area; all participants were receiving standard care (metformin therapy plus diet and exercise education) and not taking insulin, and were described as sedentary (less than 1 hour of exercise per week) and weight stable for the 6 months before the intervention.
The exercise regimen consisted of 6 weeks of CrossFit training, performed at a gym under the instruction of a certified CrossFit trainer. Groups of two to four adults performed three exercise training sessions per week, including one high-intensity workout ranging in duration from 10 to 20 minutes. At baseline and after the intervention, participants underwent a 75-g oral glucose tolerance test and a 12-lead electrocardiogram submaximal exercise stress test and provided blood samples; body composition was assed via DXA.
Overall, participants saw a mean reduction of 1.1% in total body fat percentage and a mean weight loss of 1.8 kg at 6 weeks; exercise capacity was also greater after training.
At 6 weeks, early-phase disposition index was improved vs. baseline (8.4 vs. 11.5; P = .02); late-phase disposition index was not increased (P = .65). The researchers noted variability in individual responses regarding disposition index. The proinsulin to insulin ratio, a measure of insulin processing inefficiency, was reduced after the intervention when compared with baseline levels (2.4 vs. 1.78; P = .04), according to the researchers.
“The intervention was quite effective at reducing total body fat, with trending reductions in body weight,” the researchers wrote. “Notably, lean mass was preserved, indicating that any changes in body weight were due to reductions in fat mass.”
The researchers noted that larger training studies are needed to explain the variability of responses to the intervention that were observed among participants in the program. – by Regina Schaffer
Disclosure: CrossFit Inc. supported this study with an investigator-initiated grant, but had no role in the study design or data analysis. One of the researchers reports receiving consulting fees from CrossFit.