Effectiveness of high-intensity interval training on glycemic control and cardiorespiratory fitness in patients with type 2 diabetes: a systematic review and meta-analysis

Aims: The aim of this systematic review and meta-analysis was to quantify the effect of high-intensity interval training (HIIT) on glycemic control and cardiorespiratory fitness compared with moderate-intensity training (MICT) and no training at all in patients with type 2 diabetes (T2D).

Methods: Relevant articles were sourced from PubMed, Embase, the Web of Science, EBSCO, and the Cochrane Library. Randomized-controlled trials were included based upon the following criteria: participants were clinically diagnosed with T2D, outcomes that included glycemic control (e.g., hemoglobin A1c); body composition (e.g., body weight); cardiorespiratory fitness (e.g., VO_2peak) are measured at baseline and post-intervention and compared with either a MICT or control group.

Results: Thirteen trials involving 345 patients were finally identified. HIIT elicited a significant reduction in BMI, body fat, HbA1c, fasting insulin, and VO_2peak in patients with type 2 diabetes. Regarding changes in the body composition of patients, HIIT showed a great improvement in body weight (mean difference: - 1.22 kg, 95% confidence interval [CI] - 2.23 to - 0.18, P = 0.02) and body mass index (mean difference: - 0.40 kg/m², 95% CI - 0.78 to - 0.02, P = 0.04) than MICT did. Similar results were also found with respect to HbA1c (mean difference: - 0.37, 95% CI - 0.55 to - 0.19, P < 0.0001); relative VO_2peak (mean difference: 3.37 ml/kg/min, 95% CI 1.88 to 4.87, P < 0.0001); absolute VO_2peak (mean difference: 0.37 L/min, 95% CI 0.28 to 0.45, P < 0.00001).

Conclusions: HIIT may induce more positive effects in cardiopulmonary fitness than MICT in T2D patients.