To test whether hypertension can cause hyperinsulinemia or insulin resistance, we performed intravenous glucose tolerance tests at 1 month and euglycemic clamps at 3 months after induction of two-kidney, one clip renovascular hypertension in rats. At 1 month, systolic pressure was higher in 21 clipped than in 12 control animals (161 +/- 5 mm Hg, range 134-187 mm Hg versus 119 +/- 3 mm Hg, range 108-146 mm Hg; p less than 0.001). Glucose tolerance, assessed as the glucose fractional disappearance rate between 3 and 11 minutes after the glucose injection, was similar in the clipped and sham groups (0.059 +/- 0.002 versus 0.056 +/- 0.002 min-1, respectively; p greater than 0.4). The total area under the insulin curve during glucose tolerance tests was also similar in the clipped and sham groups (926 +/- 95 versus 869 +/- 126 microunits/ml x min; p greater than 0.4). There was no significant relation between systolic blood pressure and insulin area during glucose tolerance tests in the clipped group, but there was a positive rectilinear relation in the control group (r = 0.66; p = 0.01). Fourteen animals had euglycemic clamps 2 months after glucose tolerance tests. At that time, systolic pressure (direct femoral measurement) was higher in the seven clipped animals (189 +/- 13 mm Hg versus 122 +/- 5 mm Hg in controls; p less than 0.001). Insulin infusions of 1 and 4 milliunits/min/kg body wt effected similar plasma insulin levels in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)