Effects of retinopathy and chronic kidney disease on long-term mortality in type 2 diabetic inpatients with normal urinary albumin or protein: a retrospective cohort study

Objective Normoalbuminuric chronic kidney disease (NA-CKD) is recognised as a distinct phenotype of diabetic kidney disease, but the role of diabetic retinopathy (DR) in predicting long-term mortality among these patients remains unclear. Here, we aimed to investigate the effects of DR and CKD on mortality in type 2 diabetic patients with normoalbuminuria. Design We conducted this study as a retrospective cohort study. Setting We collected clinical information from the medical records of a public medical centre in central Taiwan. Participants Patients with type 2 diabetes (n=665) who were hospitalised due to poor glucose control were consecutively enrolled and followed for a median of 6.7 years (IQR 4.1-9.6 years). Patients with either urinary protein excretion >150mg/day or urine albumin excretion >30mg/day were excluded. Primary outcome measure All-cause mortality served as the primary follow-up outcome, and the mortality data were obtained from the national registry in Taiwan. Results The patients with CKD and DR showed the highest mortality rate (log-rank p<0.001). The risks of all-cause mortality (HR 2.263; 95% CI 1.551 to 3.302) and cardiovascular mortality (HR 2.471; 95%CI 1.421 to 4.297) were significantly greater in patients with CKD and DR than in those without CKD or DR, after adjusting for the associated risk factors. Conclusions DR is an independent predictor for all-cause and cardiovascular mortality in type 2 diabetic inpatients with normoalbuminuria. Moreover, DR with CKD shows the highest risks of all-cause and cardiovascular mortality among these patients. Funduscopy screening can provide additive information on mortality in patients with type 2 diabetes, even among those with NA-CKD.