Exercise intensity does not affect glucose disposal in euglycemic abdominally obese adults

Background and aims: Loss of post-meal glycemic control is an early event in the progression from euglycemia to type 2 diabetes (T2D). The aim of the study was to examine the impact of exercise intensity on blood glucose and insulin responses to an oral glucose tolerance test (OGTT) in abdominally obese adults at risk for developing diabetes. Methods: Fourteen abdominally obese adults (age 24.8±4.3 yrs; BMI 37.9±5.2 kg·m²; % body fat 42.4±8.3%; VO₂peak 17.5±3.8 ml·kg ^-1·min^-1) completed a VO₂peak/lactate threshold (VO₂/LT) protocol plus 4 randomly assigned experimental conditions; 1) no exercise (NE); 2) low intensity (LIE; 50% difference between LT and rest), 3) moderate intensity (MIE; LT); and 4) high intensity (HIE; 50% difference between LT and VO₂peak). Sessions were calorically equivalent to 840 kJ. A 75-g OGTT was administered 1 hr after exercise onset. Glucose and insulin were assayed from blood samples collected pre-exercise/NE, post-exercise/NE, and 30-min intervals during the OGTT. Results: There were no significant differences among conditions in OGTT 180-min AUC for glucose (NE 1262.1±68.2; LIE 1297.1±175.3; MIE 1298.8±228.5; HIE 1272.6±191.0 (mmol·l^-1; p=0.72) or insulin (NE 14469±6095; LIE 16270±8470; MIE 16374±6981; HIE 17056±8425; (μIU·ml^-1; p=0.29). Insulin AUC over the first 60 min of the OGTT was significantly higher after both HIE and MIE compared to NE (p=0.05 and p=0.02, respectively). In two subjects with normal fasting glucose (NFG), but impaired glucose tolerance (IGT), high intensity exercise appeared to lower the postprandial glucose excursions. Conclusion: In young non-diabetic abdominally obese adults with NFG, a single bout of exercise did not alter post-prandial glucose and insulin responses compared to a no-exercise control session.