Effect of High-Intensity Interval Training on Glycemic Control in Adults With Type 1 Diabetes and Overweight or Obesity: A Randomized Controlled Trial With Partial Crossover

Abstract

Objective: To study the effect of 12 weeks of high-intensity interval training (HIIT) on glycemic control in adults with type 1 diabetes and overweight or obesity.

Research design and methods: Thirty inactive adults with type 1 diabetes who had BMI ≥25 kg/m2 and HbA1c ≥7.5% were randomized to 12 weeks of either HIIT exercise intervention consisting of 4 × 4-min HIIT (85-95% peak heart rate) performed thrice weekly or usual care control. In a partial crossover design, the control group subsequently performed the 12-week HIIT intervention. The primary end point was the change in HbA1c from baseline to 12 weeks. Glycemic and cardiometabolic outcomes were measured at 0, 12, and 24 weeks.

Results: Participants were aged 44 ± 10 years with diabetes duration 19 ± 11 years and BMI 30.1 ± 3.1 kg/m2. HbA1c decreased from 8.63 ± 0.66% at baseline to 8.10 ± 1.04% at 12 weeks in the HIIT intervention group (P = 0.01); however, this change was not significantly different from the control group (HIIT -0.53 ± 0.61%, control -0.14 ± 0.48%, P = 0.08). In participants who undertook at least 50% of the prescribed HIIT intervention, the HbA1c reduction was significantly greater than control (HIIT -0.64 ± 0.64% [n = 9], control -0.14 ± 0.48% [n = 15], P = 0.04). There were no differences in insulin dose, hypoglycemia on continuous glucose monitoring, blood pressure, blood lipids, body weight, or body composition between groups.

Conclusions: Overall, there was no significant reduction in HbA1c with a 12-week HIIT intervention in adults with type 1 diabetes. However, glycemic control may improve for people who undertake HIIT with greater adherence.

© 2020 by the American Diabetes Association.

Figures

Figure 1

CONSORT diagram of the randomized controlled trial with partial crossover.

Figure 2

The change in HbA1c for individual participants. A: HIIT group where 0–12 weeks involved the HIIT intervention, and 12–24 weeks involved continued, unsupervised HIIT. B: Control group where 0–12 weeks involved inactive control, and 12–24 weeks involved the HIIT intervention as the crossover design. C: Change in HbA1c from 0 to 12 weeks between the HIIT and control groups as the primary study end point. D: Predefined secondary end point for change in HbA1c from preexercise to postexercise for all 24 participants who undertook 12 weeks of HIIT. Bold line indicates the mean HbA1c. Data are mean ± SEM. *P < 0.05 change from preexercise. RCT, randomized controlled trial.