The Relationship Between Renal Function and Diabetic Retinopathy in Patients with Type 2 Diabetes: A Three-year Prospective Study

Objective: To explore the association of diabetic retinopathy (DR) and diabetic macular edema (DME) with renal function in patients with type 2 diabetes mellitus (T2DM).

Design: A prospective cohort study.

Methods: This single-centre study included patients with no DR, mild non-proliferative DR (NPDR), and no DME at baseline. DR and DME were assessed using 7-field fundus photography and swept-source OCT (SS-OCT). The baseline renal function assessed included the estimated glomerular filtration rate (eGFR) and microalbuminuria (MAU). Cox regression analyses were used to assess the hazard ratio (HR) of renal function with the progression of DR and the development of DME.

Results: A total of 1409 patients with T2DM (1409 eyes) were included. During 3 years of follow-up,143 patients had DR progression, and 54 patients developed DME. Low eGFR levels at baseline were associated with the development of DR (HR, 1.044 per 1-SD decrease; 95% CI, 1.035-1.053; P < 0.001). Compared to the participants with eGFRs >90 mL/min/1.73 m, the participants with eGFRs of 60-90 mL/min/1.73 m (HR, 1.649; 95% CI, 1.094-2.485; P = 0.017) or < 60 mL/min/1.73 m (HR, 2.106; 95% CI, 1.039-4.269; P = 0.039) had a higher risk of DR progression. Increasing MAU tertiles were associated with progression of DR (Tertile 2: HR, 2.577; 95% CI, 1.561-4.256; P < 0.001; Tertile 3: HR, 3.135; 95% CI, 1.892-5.194; P < 0.001). No significant relationship was found between renal function and the development of DME (P > 0.05).

Conclusions: Abnormal renal profiles (i.e., low levels of eGFR and high levels of MAU) were associated with the progression of DR, but not with the development of DME.