Influence of metabolic control and duration of disease on microvascular dysfunction in diabetes assessed by laser Doppler anemometry

A reduced and delayed postocclusive reactive hyperaemia has been demonstrated in diabetic patients using videophotometric capillaroscopy and laser Doppler fluxmetry. The aim of the present study was to examine by means of the new technique of laser Doppler anemometry whether impairment of skin microcirculation differs between type 1 and type 2 diabetic patients especially with regard to metabolic control and duration of diabetes. Sixteen type 1 and 19 type 2 diabetic patients were investigated and subdivided in patients with "good" (HbA1c < 7.5%) or "bad" (HbA1c > 7.5%) metabolic control and in patients with a diabetes duration of less or more than 10 years. Two age- and sex-matched groups comprising 16 and 19 non-diabetic subjects served as controls. The capillary blood cell velocity (CBV) was measured in the dorsal middle phalangeal area during rest and after 3-min arterial occlusion. In type 1 diabetic patients we found a reduced peak CBV (0.69 +/- 0.08 mm/s vs. 0.96 +/- 0.07 mm/s, p < 0.05) and a prolonged time to peak CBV (33.8 +/- 4.8 s vs. 13.6 +/- 1.9 s, p < 0.001). The delay of the postocclusive reactive hyperaemia was shown not only in patients with a diabetes duration of more than 10 years and HbA1c values above 7.5% but also in patients with a shorter disease duration and better metabolic control. In type 2 diabetes time to peak CBV (46.8 +/- 8.5 s vs. 16.4 +/- 2.2 s, p < 0.001) was also prolonged already in the first 10 years of the disease. However with regard to metabolic control a reduced peak CBV (0.54 +/- 0.04 mm/ s vs. 0.70 +/- 0.04 mm/s, p < 0.05) and a prolonged time to peak CBV (56.6 +/- 14.8 s vs. 13.7 +/- 2.7 s, p < 0.01) was found in type 2 diabetes only in the group of patients with HbA1c > 7.5%. The results indicate that in type 2 diabetes actual metabolic control might be of greater importance for the microvascular dysfunction than in type 1 diabetes and that the skin capillary circulation is impaired already in the first 10 years of both diabetes types.