Diabetic retinopathy and kidney involvement in adults with type 2 diabetes in high-altitude Tibet: A cross-sectional subanalysis of the China National Diabetic Chronic Complications Study

Abstract

Objective: To estimate the prevalence, severity, awareness, and clinical correlates of diabetic retinopathy among adults with type 2 diabetes living at very high altitude in Tibet. Methods: This cross-sectional, community-based subanalysis used prospectively collected data from the China National Diabetic Chronic Complications Study data. Adults with physician-diagnosed type 2 diabetes from three Tibet sites (3650–4300 m) with ≥1 gradable nonmydriatic fundus photograph were included (N = 320). Diabetic retinopathy was centrally graded using the International Clinical scale. Vision-threatening diabetic retinopathy was defined as severe nonproliferative or proliferative diabetic retinopathy. Kidney indices included the urinary albumin-to-creatinine ratio and estimated glomerular filtration rate. Parsimonious multivariable logistic regression (complete-case n = 318) was used to evaluate correlates of any diabetic retinopathy. Results: The prevalence of any diabetic retinopathy was 16.6% (95% confidence interval: 12.9–21.0), whereas vision-threatening diabetic retinopathy was observed in 4.4% of participants (95% confidence interval: 2.6–7.2). Diabetic retinopathy was predominantly nonproliferative, and proliferative diabetic retinopathy was rare (0.3%). Only 36.5% of participants with diabetic retinopathy reported prior awareness. Higher urinary albumin-to-creatinine ratio and estimated glomerular filtration rate <60 mL/min/1.73 m2 were independently associated with diabetic retinopathy, whereas glycated hemoglobin was not significant after adjustment. Conclusions: In community-dwelling Tibetans with type 2 diabetes living at very high altitude, diabetic retinopathy is common, awareness is low, and markers of kidney damage are strongly associated with diabetic retinopathy, supporting integrated retinal–renal screening.