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

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 ill the Study. Two intravenous glucose tolerance tests (0.5g/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 (HRmax)followed by five minutes at 85% of the HRmax. 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) x 10(-4)/(mu U/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)) x S-I and the product of fasting insulin (I-B) x 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 Si and should probably be used with caution in the follow-up of exercise protocols in diabetic patients. (C) 2008 Elsevier Masson SAS. All rights reserved.