Effect of HIIT Training Modality in People with Pre-Diabetes

Objectives: Prediabetes is characterized by elevated blood glucose levels associated with insulin resistance, increasing the risk of progression to type 2 diabetes mellitus (T2DM) and cardiovascular disease. High-intensity interval training (HIIT) has emerged as an effective non-pharmacological strategy to improve insulin sensitivity and cardiorespiratory fitness. This study aimed to analyze the effects of HIIT alone or combined with a hypocaloric diet on metabolic and cardiorespiratory parameters in individuals with prediabetes. Methods: A controlled, longitudinal, single-blind intervention study enrolled 68 adults with prediabetes (mean age 42.22-46.60 years; 73.5% women) and randomized them to HIIT plus hypocaloric diet (n = 23), HIIT only (n = 23), or hypocaloric diet only (n = 22) for 13 weeks, with pre/post assessments of glucose, VO₂max, blood pressure, FINDRISC. Results: Significant post-intervention differences were observed among groups in body mass index (p = 0.049), VO₂max (p < 0.001), fasting glucose (p < 0.001), systolic blood pressure (p < 0.001), and diabetes risk (p = 0.038), with the greatest improvements consistently observed in Group A. In Group A, fasting glucose decreased from 111.94 to 91.28 mg/dL (-20.66 mg/dL; -18.5%), VO₂max increased from 21.27 to 24.02 mL·kg^-1·min^-1 (+2.75; +12.9%), and systolic blood pressure decreased from 163.56 to 150.13 mmHg (-13.43 mmHg; -8.2%). No significant between-group differences were found for body weight (p = 0.271) or waist circumference (p = 0.174). Conclusions: HIIT combined with a hypocaloric diet is an effective and safe strategy for managing prediabetes, producing superior improvements in cardiorespiratory fitness, glycemic control, and reduction in diabetes risk compared with either intervention alone.