Microcirculation in hyperglycemic patients with IDDM without diabetic complications--effect of low-dose...

In patients with insulin-dependent diabetes mellitus (IDDM) angiotensin-converting enzyme inhibitors (ACEI) have been demonstrated to have beneficial effects in the secondary prevention of microvascular complications. There are only few data available regarding the effect of ACEI on microcirculation in patients with IDDM without any microvascular complications. In addition, there is little knowledge about ACEI action during acute hyperglycemia. In a pilot study nine patients with IDDM without any clinical signs of diabetic complications (5 females, 4 males, aged 33.3 +/- 1.0 years, duration of diabetes 11.4 +/- 3.0 years, HbA1 7.2 +/- 0.2% [normal range 4.8-7.4%], BMI 21.4 +/- 0.5 [kg/m2]) received 1.25 mg of the ACEI ramipril (Delix, Hoechst Marion Roussel, Frankfurt) over 4 weeks. Nine healthy volunteers (4 females, 5 males, age 27.4 +/- 1.1 years, HbA1 5.9 +/- 0.2% (p < 0.01 vs patients), BMI 22.2 +/- 0.9 [kg/m2]) served as controls. Using nailfold capillaroscopy we determined capillary blood cell velocity (CapiFlow, Lawrenz Electronics, Sulzbach, Germany) before and during post-occlusive hyperemia (200 mmHg for 3 minutes) as a provocative test. Before and after treatment patients were studied during hyperglycemia (blood glucose 250-350 mg/dl). Treatment with low-dose ramipril resulted in a significant decrease in the time to peak capillary blood cell velocity during post-occlusive hyperemia (17.8 +/- 7.7 vs 57.4 +/- 12.8 s, p < 0.01) in hyperglycemic patients. This effect was absent in healthy volunteers. Hemodynamic and metabolic parameters remained unchanged throughout the study in both groups. These data demonstrate that low-dose therapy with the ACEI ramipril is able to improve microcirculation in hyperglycemic patients with type 1 diabetes mellitus also before microvascular complications are evident. Prospective studies are necessary to evaluate whether this effect might be clinically relevant in the primary prevention of diabetic microangiopathy.