Objective: Albuminuria is thought to be a biomarker of microvascular and macrovascular endothelial dysfunction. However, direct evidence for an association of microvascular endothelial dysfunction with albuminuria is limited. In addition, experimental data suggest a stronger association of microvascular endothelial dysfunction with albuminuria in individuals with than in those without diabetes.
Methods: We examined cross-sectional associations of flicker light-induced retinal arteriolar dilation (n = 2095) and heat-induced skin hyperemia (n = 1508) with 24-h albuminuria in the population-based, diabetes-enriched Maastricht Study. We used linear regression analyses to adjust for age, sex, type 2 diabetes, and cardiovascular disease risk factors. In addition, we tested for statistical interaction with type 2 diabetes.
Results: Median [interquartile range] albuminuria was 6.5 [3.9-11.6] mg/24 h and 8.2% had albuminuria at least 30 mg/24 h. After adjustment, albuminuria was 1.168 (95% confidence interval, 1.046-1.303) times greater in participants in the quartile with the smallest flicker light-induced retinal arteriolar dilation relative to those with the greatest dilation, and this association was stronger in participants with type 2 diabetes (Pinteraction < 0.10). Further, each 100 percentage points lower heat-induced skin hyperemia was associated with a 1.022 (1.010-1.035) times greater albuminuria in participants with type 2 diabetes, whereas it was not associated with albuminuria in nondiabetic participants (Pinteraction < 0.10).
Conclusion: This is the first population-based study that provides direct evidence that microvascular endothelial dysfunction is associated with albuminuria, and that this association is stronger in individuals with than in those without type 2 diabetes.