Sublingual microvasculature in diabetic patients.

Diabetes is associated with micro- and macrovascular complications. The aim of the study was to investigate microvascular parameters (glycocalyx dimensions, perfused and total capillary density) in vivo in patients with type 1 and type 2 diabetes mellitus. In vivo sublingual videomicroscopy using sidestream darkfield - derived imaging was performed in 36 patients with diabetes mellitus (type 1: n = 20, type 2: n = 16) and compared to a control group of 36 healthy volunteers. Patients with HbA1c levels ≥ 8% had a significantly higher perfused boundary region (PBR; signifying the loss of glycocalyx dimensions) compared to patients with HbA1c levels < 8%, which was more pronounced in type 1 diabetes (2.08 μm [1.95-2.16 μm] vs.1.9 μm [1.66-1.94 μm], p = .029). Capillary density did not differ significantly between patients with diabetes and healthy controls. PBR was inversely related to RBC filling percentage and perfused capillary density in diabetic patients (r = -0.754, p < .001 and r = -0.505, p = .002, respectively) as well as in healthy volunteers (r = -0.701, p < .001 and r = -0.150, p = n.s.) signifying the association between glycocalyx dimensions and microvessel perfusion. Renal parameters were associated with microvascular perfusion in patients with type 2 diabetes (correlation between eGFR and perfused capillary density: r = 0. 568, p = .027/RBC filling percentage: r = 0.657, p = .008). In addition, the ratio of perfused/total capillary density correlated with CRP levels in type 2 diabetes (r = 0.682, p = .021). In conclusion, diabetes is associated with loss of glycocalyx density.