Effects of acute exercise on insulin sensitivity, glucose effectiveness and disposition index in type 2 diabetic patients

Abstract

Aim The aim of this work was to quantify the magnitude of changes in insulin sensitivity ( S I) and glucose effectiveness ( S G) in response to acute exercise in type 2 diabetic (T2D) patients, as previously studied in non-diabetic subjects. Methods Seven T2D patients and seven non-diabetic controls participated in the study. Two intravenous glucose tolerance tests (0.5 g/kg) with frequent blood sampling over 180 minutes and mathematical modelling were carried out in a randomized fashion, one at rest and the other immediately following 15 minutes of exercise at 50% of the maximum theoretical heart rate ( HR max) followed by five minutes at 85% of the HR max. S I and S G were calculated using Bergman's minimal model. Results After exercise, S I was increased by 773% (from 0.62 ± 0.16 to 5.41 ± 1.59 min −1 × 10 −4/(μU/mL) and even reached the zone of control values at rest (5.52 ± 2.28), whereas S G remained unchanged. The disposition index acute insulin response (AIR G) × S I and the product of fasting insulin ( I B) × S I also increased after exercise. Conclusion A single bout of exercise at moderate intensity in type 2 diabetics did not improve S G, but markedly improved the low S I values found in these patients, indicating that the acute effects of exercise on S I are quantitatively important in the interpretation of training-related S I changes and may even be therapeutically useful on their own. Surrogates such as homoeostasis model assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI) were not sensitive enough to detect this increase in S I and should probably be used with caution in the follow-up of exercise protocols in diabetic patients.