Comparative effects of long- and short-interval aerobic high-intensity interval training on glycemic control among...

This study aimed to systematically compare and rank the relative efficacy of moderate-intensity continuous training (MICT), short-interval high-intensity interval training (HIIT-S), and long-interval HIIT (HIIT-L) on glycemic control among individuals with type 2 diabetes (T2D) using a network meta-analysis (NMA).

Following the PRISMA-NMA guidelines, we searched PubMed, Embase, Cochrane Library, and Web of Science from database inception to October 24, 2025. Randomized controlled trials (RCTs) comparing the effects of HIIT, MICT, or non-exercise control (CON) on glycemic outcomes among individuals with T2D were included. Based on the intensity of training and durations of each high-intensity interval, aerobic HIIT was further classified into HIIT-S (≤ 60 s) and HIIT-L (≥ 2 min). The primary outcomes were glycated hemoglobin (HbA1c) and fasting plasma glucose (FPG). The homeostatic model assessment for insulin resistance (HOMA-IR) was included post hoc as an exploratory secondary outcome. A Bayesian NMA using random-effects models was implemented using the gemtc package in R. Effect sizes were expressed as mean differences (MDs) with 95% credible intervals (CrIs), and interventions were ranked through the Surface Under the Cumulative Ranking curve (SUCRA). This study was prospectively registered on PROSPERO (CRD420251175046).

In total, sixteen RCTs involving 744 participants with T2D were included. Among them, fifteen studies reported HbA1c, thirteen reported FPG, and seven reported HOMA-IR. For HbA1c, MICT (MD = - 0.47, 95% CrI: -0.77 to - 0.17), HIIT-S (MD = - 0.50, 95% CrI: -0.84 to - 0.18), and HIIT-L (MD = - 0.85, 95% CrI: -1.16 to - 0.55) all significantly reduced HbA1c levels relative to CON. Moreover, HIIT-L was significantly more effective than MICT (MD = - 0.38, 95% CrI: -0.76 to - 0.01), whereas no significant difference was observed between HIIT-L and HIIT-S (MD = - 0.34, 95% CrI: -0.76 to 0.08). However, the HIIT-L versus MICT comparison was no longer statistically significant in a sensitivity analysis excluding Winding et al. (MD = - 0.35, 95% CrI: -0.74 to 0.05). For FPG, MICT (MD = - 0.77, 95% CrI: -1.10 to - 0.43), HIIT-S (MD = - 0.85, 95% CrI: -1.21 to - 0.52), and HIIT-L (MD = - 1.12, 95% CrI: -1.54 to - 0.70) all significantly reduced FPG levels relative to CON, whereas no significant differences were observed among the active exercise interventions. Based on the SUCRA rankings, HIIT-L ranked highest for both HbA1c (97.41%) and FPG (92.31%). For HOMA-IR, only HIIT-L showed a significant reduction compared with CON (MD = - 0.84, 95% CrI: -1.74 to - 0.06), whereas MICT and HIIT-S did not. However, because HOMA-IR was included post hoc as an exploratory outcome, and because the available evidence was limited and produced wide credible intervals, these findings should be interpreted cautiously.

Current evidence indicates that MICT, HIIT-S, and HIIT-L are all associated with reductions in HbA1c and FPG compared with CON among individuals with T2D. HIIT-L had the highest ranking probabilities and the largest point estimates for both outcomes. Although the primary analysis suggested a greater reduction in HbA1c with HIIT-L than with MICT, this comparison was not robust to the exclusion of Winding et al. HIIT-S also improved glycemic control and may represent a practical alternative because each high-intensity work interval is shorter, although its feasibility and tolerability require direct evaluation. Future high-quality, volume-matched RCTs directly comparing HIIT-S and HIIT-L are needed to clarify the clinical utility of different aerobic HIIT protocols for T2D.

PROSPERO CRD420251175046.