Correlation between markers of renal function and sight-threatening diabetic retinopathy in type 2 diabetes: a longitudinal study in an Indian clinic population

INTRODUCTION: Previous epidemiological studies have reported on the prevalence of diabetic kidney disease (DKD) and diabetic retinopathy (DR) from India. The aim of this study is to evaluate the effect of DKD on the development of new-onset DR and sight-threatening diabetic retinopathy (STDR) in Asian Indians with type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: The study was done on anonymized electronic medical record data of people with T2D who had undergone screening for DR and renal work-up as part of routine follow-up at a tertiary care diabetes center in Chennai, South India. The baseline data retrieved included clinical and biochemical parameters including renal profiles (serum creatinine, estimated glomerular filtration rate (eGFR) and albuminuria). Grading of DR was performed using the modified Early Treatment Diabetic Retinopathy Study grading system. STDR was defined as the presence of proliferative diabetic retinopathy (PDR) and/or diabetic macular edema. DKD was defined by the presence of albuminuria (≥30 µg/mg) and/or reduction in eGFR (<60 mL/min/1.73 m(2)). Cox regression analysis was used to evaluate the hazard ratio (HR) for DR and STDR. RESULTS: Data of 19 909 individuals with T2D (mean age 59.6±10.2 years, mean duration of diabetes 11.1±12.1 years, 66.1% male) were analyzed. At baseline, DR was present in 7818 individuals (39.3%), of whom 2249 (11.3%) had STDR. During the mean follow-up period of 3.9±1.9 years, 2140 (17.7%) developed new-onset DR and 980 individuals with non-proliferative DR (NPDR) at baseline progressed to STDR. Higher serum creatinine (HR 1.5, 95% CI 1.3 to 1.7; p<0.0001), eGFR <30 mL/min/1.73 m(2) (HR 4.9, 95% CI 2.9 to 8.2; p<0.0001) and presence of macroalbuminuria >300 µg/mg (HR 3.0, 95% CI 2.4 to 3.8; p<0.0001) at baseline were associated with increased risk of progression to STDR. CONCLUSIONS: DKD at baseline is a risk factor for progression to STDR. Physicians should promptly refer their patients with DKD to ophthalmologists for timely detection and management of STDR.