[Prevention of type 2 diabetes mellitus due to antihypertensive treatment affecting renin-angiotensin system].

Hypertension is often associated with an impairment of glucose tolerance and is a risk factor for the development of type 2 diabetes mellitus. The occurrence of diabetes may be also influenced by the selection of the type of antihypertensive treatment. While it has been shown that the use of older type antihypertensives - diuretics and beta-blockers - may precipitate diabetes, newer drugs which inhibit the renin-angiotensin system have a positive effect on glucose tolerance. Several recent clinical trials of ACE-inhibitors and AT1-blockers have demonstrated a decreased risk of the occurrence of diabetes in comparison with placebo or conventional antihypertensive drugs. The mechanisms responsible for the antidiabetic effect of these newer antihypertensive agents remain largely speculative. Insulin resistance may be improved in several ways, e.g. by changes in microcirculation or direct effects on insulin response and glucose transport in target organ cells. However, as shown in experimental studies, improved islet function and insulin secretion may also have role due to an inhibitory effect on the local renin-angiotensin system in the pancreas. Ongoing prospective clinical trials having the occurrence of diabetes as a primary specified endpoint should confirm the preventive potential of the inhibitors of the renin-angiotensin system. Since direct comparisons are lacking, current data are inconclusive as to the superiority of one of the two classes of these inhibitors or of any single drug. Nevertheless, inhibitors of the renin-angiotensin system should definitely represent first choice antihypertensive agents for persons with additional risk factors such as family history of diabetes, obesity or impaired glucose tolerance.