Leisure time physical activity and insulin resistance in young obese students with hypertension

To investigate the hypothesis that insulin resistance plays a role in the etiology of hypertension and hyperlipidemia, we measured serum lipid levels, the fasting glucose/insulin ratio, and the insulin response to oral glucose (GTT) in a group of young obese subjects (n = 21) with hypertension and normal glucose tolerance and in normotensive subjects (n = 36) with normal glucose tolerance, matched for age and body mass index. Leisure time physical activity was evaluated by a questionnaire outlining three levels of physical activities during leisure time. Subjects with hypertension had higher fasting serum insulin (19 +/- 2 v 13 +/- 1 microU/mL, P < .01) and lower fasting glucose/insulin ratio (5.3 +/- 0.2 v 7.1 +/- 0.5 mg/dL/microU/mL, P < .01) than normotensive subjects. Subjects with hypertension had higher peak serum insulin and lower plasma glucose area/insulin area ratio in response to glucose (1.8 +/- 0.2 v 2.4 +/- 0.2 mg/dL/microU/mL, P < .05) than normotensive subjects. Serum total cholesterol, low-density cholesterol, and triglycerides were higher in the obese hypertensive subjects than in obese normotensive ones. Blood pressure correlated with either fasting serum insulin, fasting glucose/insulin ratio, or glucose area/insulin area ratio during GTT. The level of leisure time physical activities was lower in obese hypertensive subjects than in obese normotensive ones. There were significant correlations between the levels of physical activity and the fasting plasma glucose/insulin ratio (r = 0.371, P < .01) or the fasting serum insulin concentration (r = -0.282, P < .05). The study provided evidence that a low level of leisure time physical activity is associated with insulin resistance and resultant hyperinsulinemia, which are the key metabolic abnormalities that link hypertension, obesity, and hyperlipidemia in young subjects.