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(1c) 5.9% [5.8-6.1%] [41.0 (39.9-43.2) mmol . mol(-1)]) 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 (P >= 0.28). However, insulin was lower in LV-HIIE (mean [95% CI] -44.4 [-23.7, -65.1] mU . L-1) and CME (-33.8 [-13.7, -53.9] mU . L-1) compared with CON. Insulin responses were greater in South Asians (interaction P = 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.

Automated summary

There were no significant differences in metabolic responses to LV-HIIE and CME between white Europeans and South Asians with nondiabetic hyperglycemia, but reductions in insulin and insulin resistance after acute exercise were more pronounced in South Asians. Further trials are needed to investigate the long-term impact of LV-HIIE and CME on cardiometabolic health.