An acute bout of 4 × 4-min or 10 × 1-min HIIT improves β cell glucose sensitivity in postmenopausal females with type 2 diabetes: a secondary analysis

Improvements in glycemic control following acute exercise are typically attributed to improved postexercise insulin sensitivity (IS) with comparatively little known about how acute exercise impacts β cell function, especially in postmenopausal females. We determined how two high-intensity interval training (HIIT) protocols, matched for total estimated energy expenditure, impact β cell function in postmenopausal females with type 2 diabetes. Thirteen postmenopausal females (70 ± 5 yr; 12 ± 7 yr since diagnosis, 80.9 ± 13.8 kg, 32.4 ± 5.6 kg·m²; HbA1c-49.8 ± 10.3 mmol/mol [6.7 ± 1.0]) living with type 2 diabetes were included in this semirandomized crossover trial. The trial involved an initial resting control condition followed by two HIIT conditions [4 × 4-min HIIT (HIIT4) and 10 × 1-min HIIT (HIIT10)] completed in a randomized order 2-4 days apart. β cell function (glucose sensitivity) and insulin sensitivity were determined from a 2-h mixed-meal tolerance test performed 2 h after rest or HIIT. Both HIIT4 and HIIT10 significantly improved β cell glucose sensitivity compared with control (15 pmol/min/m²/[mmol/L], [95% confidence interval (CI) 6, 23]; <i>P</i> = 0.002 and 16 pmol/min/m²/[mmol/L], [95% CI 7, 25]; <i>P</i> = 0.002, respectively), with no difference between HIIT protocols (1 [-8, 10], <i>P</i> = 0.79). There were no significant differences in IS metrics (Matsuda index, OGIS, Stumvoli, and QUICKI) between the conditions. An acute bout of 4 × 4-min or 10 × 1-min HIIT improves β cell glucose sensitivity in postmenopausal females living with type 2 diabetes. ClinicalTrials.gov: NCT04986345.<b>NEW & NOTEWORTHY</b> This is the first study to explore the effects of acute high-intensity interval training (HIIT) on β cell function in postmenopausal women with type 2 diabetes. Our crossover trial compares two HIIT protocols, matched for total estimated energy expenditure, examining their impacts on β cell function and insulin sensitivity. Despite the absence of an insulin-sensitizing effect, we show robust effects of HIIT on β-cell function, including an improvement in β-cell glucose sensitivity.