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 >150 mg/day or urine albumin excretion >30 mg/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.