Choroidal thickness in relation to urinary albumin excretion rate in type 2 diabetes mellitus without retinopathy

Background To evaluate choroidal thickness (CT) in diabetic patients without diabetic retinopathy (DR) in relation to the urinary albumin excretion rate (UAER). Methods This is a prospective case-control study that included a consecutive sample of 120 patients with type 2 diabetes without clinically evident DR and a group of 60 matched healthy controls. Diabetic patients were included in two groups according to their UAER (normoalbuminuria and microalbuminuria). Complete ophthalmological examination was performed followed by optical coherence tomography (SD-OCT) for retinal and choroidal assessment. Twenty-four-hour urine samples were collected for UAER and blood samples for HbA1c and serum creatinine were obtained. Results The study included 180 eyes from 180 subjects in three groups. Patients with higher levels of albuminuria had a thinner choroid than normal controls, with decremental thinning as albuminuria progressed. Diabetics with normoalbuminuria showed no significant differences from controls. Choroidal thickness showed a significant moderate negative correlation with UAER (r = − 0.58, p < 0.001). Multiple regression analyses for diabetic patients with microalbuminuria demonstrated that UAER is the most important determinant of subfoveal choroidal thickness (SFCT) (p < 0.001). Conclusions Decreased CT was significantly correlated with UAER in diabetic patients without retinopathy and otherwise normal kidney functions. This decrease in thickness might be a predictor of DR.