Insulin Sensitivity in Patients with Essential Hypertension: No Influence of the ACE Inhibitor Enalapril

We studied the effect of an ACE inhibitor (Enalapril [ENA], 10 mg o.d.) and a calcium-channel blocker (Nitrendipine [NIT], 20 mg o.d.) on insulin sensitivity in a double-blind cross-over study. Insulin sensitivity was measured by a two-step hyperinsulinemic euglycemic clamp. Serum potassium concentrations were kept constant during the clamp procedure by means of a variable potassium infusion. Twenty patients with essential hypertension (age 35 ± 12 years [mean ± SD], BMI 31.9 ± 5.0 kg/m², initial blood pressure 152 ± 10/99 ± 6 mmHg) were treated with ENA or NIT for 4 weeks, respectively, with a wash-out period of 3 weeks. No carry-over effects or period effects were observed. Both drugs induced a comparable decline in systolic and diastolic blood pressure (ENA - 15 ± 9/- 13 ± 8 mmHg, NIT - 16 ± 8/- 12 ± 6 mmHg). No significant change in body weight occurred with both treatments (ENA - 0.4 ± 2.0; NIT 0.6 ± 1.1 kg). Neither drug had a significant impact on any parameter of insulin sensitivity measured (e.g. insulin sensitivity index S_I: ENA 5.2 ± 2.0 [basal 5.1 ± 2.2], NIT 5.8 ± 3.0 [basal S_I 5.1 ± 2.4) ml/min × m²/µU/ml). In conclusion, no significant differences between ENA and NIT on insulin sensitivity were observed. The reduction of blood pressure had no apparent effect on insulin sensitivity.

Key words

Hypertension - ACE Inhibitor - Calcium-Channel Blocker - Two-Step Hyperinsulinemic Euglycemic Glucose Clamp - Potassium Homeostasis