Improvements in Glycemic Control After Acute Moderate-Intensity Continuous or High-Intensity Interval Exercise Are Greater in South Asians Than White Europeans With Nondiabetic Hyperglycemia: A Randomized Crossover Study.

Objective: To examine whether circulating metabolic responses to low-volume high-intensity interval exercise (LV-HIIE) or continuous moderate-intensity aerobic exercise (CME) differ between white Europeans and South Asians with nondiabetic hyperglycemia (NDH).

Research Design And Methods: Thirteen white Europeans and 10 South Asians (combined median [interquartile range] age 67 [60-68] years, HbA 5.9% [5.8-6.1%] [41.0 (39.9-43.2) mmol ⋅ mol]) completed three 6-h conditions (sedentary control [CON], LV-HIIE, and CME) in a randomized order. Exercise conditions contained a single bout of LV-HIIE and CME, respectively (each ending at 2 h), with meals provided at 0 and 3 h. Circulating glucose (primary outcome), insulin, insulin resistance index (IRI), triglycerides, and nonesterified fatty acids were measured at 0, 0.5, 1, 2, 3, 3.5, 4, 5, and 6 h. Data were analyzed as postexercise time-averaged area under the curve (AUC) adjusted for age, sex, and preexercise AUC.

Results: Glucose was similar in each condition and with ethnicity, with no condition-by-ethnicity interaction ( ≥ 0.28). However, insulin was lower in LV-HIIE (mean [95% CI] -44.4 [-23.7, -65.1] mU ⋅ L) and CME (-33.8 [-13.7, -53.9] mU ⋅ L) compared with CON. Insulin responses were greater in South Asians (interaction = 0.03) such that values were similar in each ethnicity during exercise conditions, despite being 33% higher in South Asians during CON. IRI followed a similar pattern to insulin. Lipids were unaffected by exercise.

Conclusions: Reductions in insulin and insulin resistance after acute LV-HIIE and CME are greater in South Asians than in white Europeans with NDH. Further trials are required to examine the longer-term impact of LV-HIIE and CME on cardiometabolic health.