Endothelial function in patients with type 1 diabetes evaluated by skin capillary recruitment

Abstract

The aim of the present study was to evaluate skin capillary density and recruitment of the upper and lower extremities of patients with type 1 diabetes under chronic treatment without clinical manifestations of diabetes-related complications. This cross-sectional observational study included 59 (27.1 ± 10.6 years) consecutive outpatients with type 1 diabetes [duration 10 (1; 45) years] and 41 age- and sex-matched healthy controls. We used intravital video-microscopy to measure basal and maximal (during venous congestion) skin capillary densities as well as capillary recruitment using post-occlusive reactive hyperemia (PORH) in the dorsum of the fingers and toes. Mean capillary density (MCD) of the fingers at baseline was not different between controls and patients (123.02 ± 22.6 and 132.3 ± 28.9 capillaries/mm 2, respectively; P = 0.08). In contrast, baseline MCD of the toes was lower in controls, when compared to patients (84.6 ± 19.8 and 96.2 ± 23.4 capillaries/mm 2, respectively; P = 0.01). Capillary recruitment during PORH (% increase of the number of capillaries/mm 2) was significantly higher in controls compared to patients both in fingers [7 (− 8; 33) and − 1.0 (− 35, 13), respectively; P = 0.000] and toes [6 (− 20; 46) and 0 (− 24; 20), respectively; P = 0.000]. During venous occlusion, capillary density increase (% increase of the number of capillaries/mm 2) was also higher in controls compared to patients both in fingers [3 (− 14; 23) and 0.0 (− 30; 29.2), respectively; P = 0.02] and toes [9.3 (− 18; 51) and − 7 (− 34; 22), respectively; P = 0.000]. Our results showed that patients with type 1 diabetes, although not presenting skin capillary rarefaction, display skin microvascular functional alterations in both extremities characterized by an absence of capillary reserve.