Short-Term Interval and Continuous Training Improves Pancreatic ß-Cell Function Adjusted for Skeletal Muscle Insulin Resistance in Adults with Prediabetes

Exercise improves pancreatic function in an energy dose-dependent manner. We previously showed that when calories are matched, an acute exercise bout changes glucose-stimulated insulin secretion (GSIS) relative to multi-organ insulin resistance (IR) in an intensity-based manner during the immediate post-exercise period in people with prediabetes. However, the impact of short-term training intensity on ß-cell function is unknown. Thus, we examined the impact of high-intensity interval and moderate-continuous training on GSIS relative to multi-organ IR in adults with prediabetes. Thirty-one adults (Age: 61±8y; BMI: 33±6 kg/m²) with prediabetes according to ADA 75g OGTT and/or HbA1c criteria were randomized to energy-matched interval (INT: 60-min/d alternating 3-min at 90 and 50% HR_peak) or continuous training (CONT: 60-min/d 70% HR_peak) for 2 weeks. Fitness (VO₂peak) and body mass were measured before and after, and a 120-min 75g OGTT with blood samples for glucose, insulin, C-peptide and FFA were determined every 30-min. GSIS (C-pep/Glc tAUC_0-120min) and ß-cell function (Disposition Index [DI: GSIS/IR]) relative to skeletal muscle (Insulin_tAUC x Glc_tAUC), hepatic (HOMA-IR) and adipose (Adipose-IR_fasting) IR were calculated. Training increased VO₂peak (+1.1±2.1 mL/kg/min), and reduced body mass (-0.6±1.1 kg) and IR (-11±31%), independent of intensity (P<0.05). INT and CONT also decreased GSIS to a similar extent (Interaction: P=0.88). Short-term training improved skeletal muscle DI by ∼24% (P<0.05), but there was no effect on hepatic or adipose DI. Collectively, short-term INT and CONT training improves ß-cell function relative to skeletal muscle, but not hepatic or adipose, IR. These data suggest unique mechanisms regulate glucose metabolism following single vs. habitual physical activity in adults with prediabetes.