# Diabetic retinopathy severity is associated with renal function deterioration in patients with diabetic kidney disease: a retrospective cohort study

## TL;DR

This study found that the severity of diabetic retinopathy is linked to faster kidney function decline in patients with diabetic kidney disease.

## Contribution

The study shows that both nonproliferative and proliferative diabetic retinopathy independently predict kidney function deterioration.

## Key findings

- Patients with proliferative diabetic retinopathy had nearly three times the risk of kidney function decline.
- Nonproliferative diabetic retinopathy was also independently associated with faster kidney deterioration.
- Hard exudates were not independently linked to kidney function decline after adjusting for other factors.

## Abstract

To investigate whether the severity of diabetic retinopathy (DR) and the presence of hard exudates (HEs) are associated with renal function deterioration in patients with diabetic kidney disease (DKD).

This is a retrospective cohort study including 140 patients with DKD. The outcome was the progression of DKD (an estimated glomerular filtration (eGFR) decline (%)>15%) over a 5-year follow-up period. A total of 101 patients had eGFR parameters during the follow-up. DR was categorized into nonproliferative DR (NPDR) and proliferative DR (PDR). HEs were identified via optical coherence tomography (OCT). Clinical and laboratory data were acquired from medical records. The influence of the severity of DR and the presence of HEs were assessed via Cox regression.

The mean follow-up time was 34.31 (± 16.36) months. A significant difference was found in eGFR decline (%) (P = 0.024) between the absent DR, NPDR and PDR groups. eGFR decline (%) was more severe in patients with HEs than in those without HEs (P = 0.011). After adjustment for age, body mass index (BMI), glycosylated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-C), systolic blood pressure, eGFR at baseline, urine albumin creatine ratio (UACR) stage at baseline, use of Sodium-Glucose Linked Transporter 2 (SGLT2) inhibitors, as well as potential confounders such as duration of Diabetic mellitus (DM), use of Renin-Angiotensin System Inhibitors (RAS) inhibitors and Glucagon-Like Peptide-1 Receptor Agonists (GLP-1RAs), Cox regression revealed that PDR (p=0.035) and NPDR (p=0.049) were independently associated with renal function deterioration. Compared with the participants in the absent DR group, participants with PDR, as well as NPDR presented a nearly threefold greater risk (adjusted HR = 2.88; 95% CI: 1.08–7.71; adjusted HR = 2.78; 95% CI: 1.004–7.70, respectively). However, the presence of HEs was not independently associated with renal function deterioration in the adjusted Cox model (P = 0.567).

DR severity was independently associated with the progression of DKD, whereas HEs were not. DKD patients with PDR as well as NPDR should undergo kidney function testing more frequently and receive early intervention to prevent renal function deterioration.