5.2: Reduced Sublingual Endothelial Glycocalyx in Type 1 Diabetics with Diabetic Nephropathy

Abstract

Background

Glycocalyx is a glycoprotein layer protecting the capillary endothelium. An impaired glycocalyx may precede the development of microvascular complications in diabetes. Capillaroscopy is a new method to estimate the dimensions of the glycocalyx by measuring the perfused boundary region (PBR). We evaluated the glycocalyx thickness in type 1 diabetic patients with different levels of historical and current albuminuria.

Methods

Cross-sectional study including 77 type 1 diabetics stratified by history of normoalbuminuria (<30 mg/g; n = 26), microalbuminuria (30–299 mg/g; n = 27) and macroalbuminuria (>300 mg/g; n = 24). Glycocalyx thickness was assessed by 5 measurements with the GlycoCheck® device, a non-invasive hand-held microscope generating video recordings of the sublingual capillaries. Endothelial glycocalyx thickness was estimated from the PBR in capillaries with a diameter range of 5–25 µm. Higher PBR indicates smaller glycocalyx width. Urinary albumin-to-creatinine ratio (UACR) was measured in 3 morning samples.

Results

In normo-, micro-, and macroalbuminurics PBR was (mean ± SD) 2.30 ± 0.22 µm, 2.32 ± 0.25 µm, and 2.49 ± 0.35 µm, respectively. Differences between normo- and macroalbuminurics and micro- and macroalbuminurics were significant (p < 0.05) in an unadjusted model and remained significant after adjustment for age, sex, HbA_1c, diabetes duration and systolic blood pressure. In pooled (n = 77) multivariate linear regression, higher level of current UACR was associated with a higher PBR (p = 0.0007). Conclusion: In type 1 diabetics with a history of macroalbuminuria, measurements with the non-invasive GlycoCheck® device revealed significantly higher PBR, suggesting an impaired glycocalyx, compared to patients with normo- or microalbuminuria.

Moreover, higher current level of albuminuria was associated with higher PBR.