[Angiotensin II type-1 receptor antagonists and diabetes mellitus]

Arterial hypertension is a major risk factor for microangiopathic diabetic complications and associated with an increased cardiovascular morbidity and mortality. An intensified antihypertensive treatment reduces microangiopathic complications and cardiovascular morbidity and mortality in diabetic patients. Even in normotensive type 1 and type 2 diabetic patients, the treatment with ACE inhibitors may prevent the later development of diabetic nephropathy. Treatment with ACE inhibitors increases the concentrations of bradykinin, which is responsible for the side effects such as cough and urticaria in some patients. On the other hand, bradykinin may have beneficial intrarenal effects decreasing the intraglomerular pressure. The novel angiotensin II receptor type 1 antagonists do not influence the bradykinin concentrations and seem to be tolerated by patients suffering from chronic cough with ACE inhibitor therapy. It is still unclear whether the different intrarenal effects are of clinical relevance in the long-term treatment of diabetic patients. In studies with diabetic animals the nephroprotective effects of ACE inhibitors and angiotensin II type 1 receptor antagonists are comparable. It was shown that glucose and lipid metabolism is not influenced by treatment with angiotensin II type 1 receptor antagonists. Further compared to Felodipine the reduction of urinary albumin excretion rate (UAER) was more pronounced by Losartane in Chinese type 2 diabetic patients. Short-term studies directly comparing the renal effects of ACE inhibitors with AT II type 1 receptor antagonists revealed similar reduction of blood pressure and albumin excretion rate in patients with diabetic nephropathy, so a combination of both substances might be useful. Data from ongoing long-term trials are still missing. Further, it is unknown whether different phenotypes of the ACE gene (DD, II polymorphism) require different therapeutic options. In conclusion, treatment with angiotensin II receptor antagonists is well-tolerated and has no adverse effects on metabolic control in diabetic patients. The beneficial effect on microangiopathic complications however has to be proven in randomized long-term studies in direct comparison with ACE inhibitors, which were clearly shown to delay the development and progression of diabetic nephropathy.