Sulfonylurea treatment of type 2 diabetic patients does not reduce the vasodilator response to ischemia

OBJECTIVE - Sulfonylureas block the activation of vascular potassium-depend ent ATP channels and impair the vasodilating response to ischemia in nondia betic individuals, but it is not known whether this occurs in type 2 diabet ic patients under chronic treatment with these drugs. Glimepiride, a new su lfonylurea, apparently has no cardiovascular interactions. The aim of our s tudy was to compare the effect of the widely used compound glibenclamide, t he pancreas-specific glimepiride, and diet treatment alone on branchial art ery response to acute forearm ischemia. RESEARCH DESIGN AND METHODS - Brachial artery examination was performed by a high-resolution ultrasound technique on 20 type 2 diabetic patients aged (mean +/- SD) 67 +/- 2 years and on 18 nondiabetic patients matched for age , hypertension, and dislipidemia. Diabetic subjects underwent three separat e at the end of each 8-week treatment period, during which they received gl ibenclamide, glimepiride, or diet alone according to crossover design. Scan s were obtained before and after 4.5 min of forearm ischemia. Postischemic vasodilation and hyperemia were expressed as percent variations in vessel d iameter and blood flow. RESULTS - Postischemic vasodilation and hyperemia were, respectively, 5.4 /- 0.90 and 331 +/- 38% during glibenclamide, 5.46 +/- 0.69 and 326 +/- 28% during glimepiride, and 5.17 +/- 0.64 and 357 +/- 35% during diet treatmen t (NS). These results were similar to those found in the nondiabetic patien ts (6.44 +/- 0.68 and 406 +/- 42%, NS). CONCLUSIONS - In type 2 diabetic patients, the vasodilating response to for earm ischemia was the same whether patients were treated with diet treatmen t alone or with glibenclamide or glimepiride at blood glucose-lowering equi potent doses.