Skin capillary density in subjects with impaired glucose tolerance and patients with type 2 diabetes

In view of recent interest in the role of impaired early development and the pathogenesis of cardiovascular disease and carbohydrate intolerance in adults, this study examines whether reduced skin capillary density contributes to the limited microvascular hyperaemic responses observed in patients with Type 2 diabetes and subjects with impaired glucose tolerance (IGT). Fifteen patients with Type 2 diabetes, 15 subjects with IGT and 15 matched non-diabetic control subjects were studied. Capillary videomicroscopy was used to record images of the skin capillaries on the dorsum of the middle phalanx of the left middle finger before and after 10 min venous occlusion at 35 mmHg. There were no significant differences between the three groups in either basal capillary density (112 (71-144) caps mm-2 Type 2 patients (median and range) vs 107 (76-140) caps mm-2 IGT subjects vs 112 (76-138) caps mm-2 control subjects; p = 0.9, Kruskal Wallis), or following venous occlusion (122 (87-157) caps mm-2 vs 121 (90-143) caps mm-2 vs 123 (81-147) caps mm-1; p = 0.9). In addition there were no differences in blood pressure, BMI or skin temperature. These results do not support the concept of impaired early development of the skin microcirculation in patients with Type 2 diabetes or IGT and suggest that mechanisms other than reduced capillary density are involved in limiting microvascular vasodilation.