Glucose metabolism in abdominally obese hypertensive and normotensive subjects.
To determine whether the combination of obesity and hypertension results in additive defects in oxidative and nonoxidative glucose metabolism and the association of these changes with altered hemodynamic actions of insulin, we studied 11 abdominally obese hypertensive, 6 abdominally obese normotensive, and 7 lean normotensive nondiabetic subjects. Endogenous glucose production and glucose metabolized were calculated from a euglycemic clamp at 72 and 287 pmol insulin/m2 per minute. Glucose metabolized divided by insulin was lower at 72 pmol/m2 per minute in both obese groups than in lean normotensive subjects, at 148 +/- 14, 144 +/- 33, and 373 +/- 69 (mumol/m2 per minute)/(pmol/L), respectively (P < .01). Similar results were obtained during the higher insulin dose. Nonoxidative and oxidative glucose disposals by indirect calorimetry were lower in both abdominally obese groups (P < .05). Hepatic glucose production was completely suppressed in lean subjects at the lower insulin dose and in all three groups at the higher insulin dose. Hemodynamic responses during the clamp were not significantly different among the three groups. Abdominal obesity is associated with defects in insulin-regulated oxidative and nonoxidative glucose disposal as well as in insulin suppression of hepatic glucose production. Mild hypertension does not exacerbate these defects. Whereas the global impairment in glucose metabolism suggests the presence of an early defect or defects, including reduced tissue perfusion, systemic and regional hemodynamic responses to insulin were not altered. These findings do not support a direct role for insulin resistance in the pathogenesis of the hypertension associated with abdominal obesity.