Renal function and its association with retinal microcirculation and choroidal thickness in type 2 diabetes: Insights from cystatin C and creatinine.

OBJECTIVE: To examine the association between renal dysfunction and macular retinal microvascular density and choroidal thickness (mCT) in type 2 diabetes mellitus (T2DM) METHODS: In this cross-sectional study, patients with T2DM underwent SS-OCTA to assess superficial (SCP) and deep (DCP) capillary plexus vessel densities, and SS-OCT to measure mCT. Renal function was evaluated using estimated glomerular filtration rate from cystatin C and creatinine (eGFRcr-cys). Regression analyses were performed to evaluate associations between eGFRcr-cys, retinal microvascular density, and mCT. Sensitivity analyses incorporated uric acid levels, and stratified analyses assessed the effect of diabetic retinopathy (DR).

RESULTS: Among 1,050 subjects, declining renal function was associated with reduced SCP-VD and mCT, but increased DCP-VD. After adjusting for confounders, eGFRcr-cys was positively associated with SCP-VD (β = 0.62) and mCT (β = 5.55), and negatively with DCP-VD (β = -0.69; all P < 0.05). These associations remained robust in sensitivity analyses. Stratified analyses revealed eGFRcr-cys was positively associated with SCP-VD and negatively with DCP-VD in non-DR patients, and positively associated with both SCP-VD and mCT in DR patients.

CONCLUSION: Retinal microcirculation changes in T2DM reflect renal dysfunction. These findings suggest its potential role in detecting early renal impairment, particularly in the absence of DR.