Association of diabetic retinopathy with kidney disease progression according to baseline kidney function and albuminuria status in individuals with type 2 diabetes

Background Whether diabetic retinopathy (DR) can predict kidney disease progression in individuals with diabetes remains unclear. Furthermore, there are only a limited number of studies investigating the association between DR and kidney outcomes classified according to baseline kidney function and albuminuria status. Here, we examined the association of DR with kidney disease progression in individuals with type 2 diabetes. Methods This retrospective cohort study included 6759 Japanese adults with type 2 diabetes (36.3% women). Kidney insufficiency and albuminuria were defined as eGFR < 60 mL/min/1.73 m2 and urinary albumin-to-creatinine ratio >= 30 mg/g, respectively. The exposure and outcome were baseline DR and the composite of eGFR halving or the initiation of kidney replacement therapy, respectively. The hazard ratios for the outcome were estimated using the multivariable Cox proportional hazards model. Results During the median follow-up period of 8.4 years, 922 reached the outcome. Among the individuals without kidney insufficiency, those with DR at baseline had a significantly higher incidence of the outcome than those without DR regardless of baseline albuminuria status (p < 0.05), whereas the presence of DR was not the risk factor among individuals with kidney insufficiency. There was an interaction between baseline DR and kidney insufficiency with respect to the outcome incidence (p = 0.043). When baseline eGFRs were classified into eGFR categories based on the Kidney Disease: Improving Global Outcomes guideline, the above findings were more clearly shown. Conclusions DR may be able to predict kidney disease progression only among individuals with type 2 diabetes exhibiting preserved kidney function.