Replacement of ACE-inhibitors by AII-receptor antagonists in hypertensive patients with type II diabetes mellitus: Metabolic and hemodynamic consequences

Background: The main pharmacodynamic difference between ACE- inhibitors (ACE-i) and AII-receptor antagonists (AII-r) is that ACE-i increase levels of bradykinin, which, in addition to vasodilation, may cause a decrease in insulin resistance. Hypertensive patients with diabetes type II suffering from side effects from ACE-i are frequently changed over to AII-r. Objective: 1. To study whether this procedure reduces metabolic control. 2. To study effects on blood pressure and fore arm blood flow (FLOW). 3. To study possible associations between the variables HbA1c and FLOW. Methods: A self-controlled sequential comparison is required to address such questions. Sixteen patients were treated with 10 mg of enalapril or equipotent doses of other ACE-i for 6 months, and, subsequently, with the AII-r losartan 50 mg daily for 6 more months. Patients were examined at the outpatient clinic every 4-8 weeks during the trial. FLOW was measured by iridium strain gauge venous occlusion plethysmography. Results: Mean arterial pressure (MAP) increased by 4 +/- 5 mm Hg (p <0.05) after 6 month losartan treatment compared to the point of withdrawal of ACE-i. FLOW decreased by 5.4 +/- 5.0 ml/100 ml tissue.min (p <0.001), and HbAlc rose by 0.6 +/- 0.8 mmol/l(p <0.05). Other metabolic variables including cholesterol, HDL cholesterol, triglycerides, were not significantly influenced by the change in therapy. Multiple regression analysis revealed that after adjustment for difference in HbAlc the correlation between FLOW and MAP was unchanged, and that after adjustment for difference in FLOW the correlation between HbAlc and MAP was not significant anymore. Conclusions: Replacement of ACE-i by AII-r in hypertensive patients with type II diabetes mellitus induced a significant rise in HbAlc and MAP, and a fall in FLOW. The associations of HbAlc and FLOW with MAP were at least partly independent of each other suggesting that mechanisms other than the bradykinin system, e.g., the AT2 receptor system, are involved. Our study design did not control for placebo and time effects, and so the data are of a preliminary nature