Feasibility and preliminary efficacy of high intensity interval training in type 2 diabetes

Aims: To compare the feasibility of high intensity interval exercise (HI-IE) versus moderate intensity continuous exercise (MI-CE) in patients with type 2 diabetes (T2D), and to investigate the preliminary efficacy of HI-IE and MI-CE for improving glycated hemoglobin A1c (HbA1c) and body composition.

Methods: Individuals with T2D were recruited and randomly assigned to HI-IE and MI-CE. Exercise training was performed 5 days per week for 12 weeks. Recruitment, retention, adherence, feeling states and self-efficacy were analyzed for feasibility. Changes in HbA1c and percent body fat from baseline were investigated at 12 weeks to determine the preliminary efficacy.

Results: Of 126 participants showing interest to join the study, 15 individuals were randomized and completed the program. No participants dropped out from the study after enrollment. Adherence rates were high and did not differ between HI-IE and MI-CE (p>0.05; >97.2% of the eligible exercise sessions for both groups). Feeling states and self-efficacy did not differ between the groups. Percent trunk fat decreased in both HI-IE and MI-CE (p=0.007 and 0.085, respectively). Total percent body fat, percent leg fat, and subcutaneous fat width were significantly reduced in both groups (p<0.05), whereas HbA1c did not change from baseline (p>0.05). The degree of improvement was similar between the interventions (p>0.05).

Conclusion: In individuals with T2D, implementing a 12-week structured HI-IE training can be as feasible as MI-CE training. Both interventions are equally effective in lowering total body fat but have little impact on HbA1c in relatively well controlled participants with T2D.