Insulin resistance in patients with essential hypertension can occur in the absence of microalbuminuria

Abstract

This study was initiated to see if the presence of resistance to insulin-mediated glucose disposal, glucose intolerance, and hyperinsulinemia in healthy patients with hypertension was dependent upon the coexistence of microalbuminuria. For this purpose we compared these variables in 68 individuals: 34 patients with hypertension and 34 normal volunteers. The two groups were similar in terms of age, gender distribution, body mass index, and ratio of waist to hip girth. Furthermore, although four patients with hypertension satisfied the criteria for microalbuminuria, as compared to one normal volunteer, the urinary albumin excretion (UAE) rates were similar in the two groups (8.07 +/- 1.08 v 7.67 +/- 1.12 micrograms/min). Despite the similarities, both the plasma glucose and insulin responses to a 75 g oral glucose challenge were significantly higher (P < .01) in those with high blood pressure. In addition, the steady-state plasma glucose (SSPG) concentrations at the end of a 180 min continuous infusion of somatostatin, insulin, and glucose was significantly higher in those with hypertension (156 +/- 13 v 107 +/- 10 mg/dL, P < .01). Since the steady-state plasma insulin levels were also somewhat higher in those with hypertension, the higher SSPG values indicate that these individuals were relatively insulin resistant as compared to the control population. Finally, UAE rates were not correlated with either the plasma glucose or insulin responses to oral glucose or to the SSPG concentrations--either in the entire group of 68, or when the 34 patients in each group were considered separately. These results demonstrate that insulin resistance, glucose intolerance, and hyperinsulinemia can occur independently of microalbuminuria in patients with hypertension.