Normal insulin response to short-term intense exercise is abolished in Type 2 diabetic patients treated with gliclazide

Background: Physical activity is an essential component of diabetes management; however, exercise is associated with the risk for metabolic decompensation. The aim of the study was to analyze insulin response to the short-term intense exercise in middle-aged Type 2 diabetic patients treated with gliclazide. Materials and Methods: Fourteen Type 2 diabetic patients (47.9 +/- 1.6 years, mean +/- S.E.M.), treated with gliclazide, and 14 healthy controls (45.1 +/- 1.0 years) were submitted to standard graduated submaximal (90% HRmax) exercise treadmill testing at 2 h after standardized breakfast. Serum glucose, insulin, proinsulin, C peptide, growth hormone, insulin-like growth factor-1, and cortisol concentrations; and plasma lactate, glucagon, epinephrine, and norepinephrine concentrations were measured during the periexercise period up to the 60th min of the recovery period. Results: Significant hemodynamic (heart rate, systolic, and diastolic blood pressure), metabolic (lactate concentration), and hormonal (epinephrine and norepinephrine levels) responses to the exercise were similar in patients and healthy subjects. Glucose, insulin, and proinsulin levels were higher in the diabetic group at the preexercise and at all the next analyzed time points. The insulin concentration increased during the postprandial period in both groups and decreased subsequently during the exercise only in the control group, without concurrent C peptide decline. The C peptide-to-insulin ratio increased during the exercise and decreased immediately postexercise only in the control group. Conclusions: The initial decrease of the insulin serum concentration during short-term intense exercise in normal middle-aged men is primarily related to the increased clearance of the hormone. Normal insulin response to the exercise was abolished in Type 2 diabetic patients treated with gliclazide. (C) 2009 Elsevier Inc. All rights reserved.