Diabetic Retinopathy and Chronic Kidney Disease: Associations and Comorbidities in a Large Diabetic Population – The Tongren Health Care Study

<b><i>Introduction:</i></b> The aim of the study was to investigate associations between diabetic retinopathy (DR) and chronic kidney disease (CKD) in patients with type 2 diabetes (TD2). <b><i>Methods:</i></b> The participants of the cross-sectional, community-based Tongren Health Care Study underwent a detailed medical and ophthalmological examination. We defined TD2 by a fasting plasma glucose concentration of ≥7.0 mmol/L or a medical history. CKD was classified as either reduced estimated glomerular filtration rate (eGFR) of &lt;60 mL/min/1.73 mm² or presence of albuminuria. DR was assessed using color fundus photographs. <b><i>Results:</i></b> Out of 62,217 participants of the Tongren Health Care Study, 5,103 (8.2%) patients had TD2. The prevalence of DR was 12.8% (95% CI, 11.8%, 13.7%), CKD was 13.3% (95% CI, 12.4%, 14.3%), and the subtypes of CKD including reduced eGFR and albuminuria was 4.6% (95% CI, 4.2%, 5.1%) and 10.1% (95% CI, 9.3%, 10.9%), respectively. DR was detectable in 21.0% of the patients with CKD, while CKD was present in 20.9% of the DR patients. Higher DR prevalence was associated with higher prevalence of albuminuria and reduced eGFR (both <i>p</i> &lt; 0.05). Factors independently associated with the presence of CKD instead of DR were older age (<i>p</i> &lt; 0.001, OR = 1.05), a higher body mass index (<i>p</i> &lt; 0.001, OR = 1.14), a higher serum concentration of triglycerides (<i>p</i> &lt; 0.001, OR = 1.26), and a lower blood glucose (<i>p</i> &lt; 0.001, OR = 0.93). Having hypertension was additionally associated with the presence of reduced eGFR as compared with DR (<i>p</i> = 0.005, OR = 4.47). <b><i>Conclusions:</i></b> TD2 patients of older age and with higher body mass index, hypertension, and dyslipidemia had a higher probability of being affected by CKD rather than DR, while those with a higher blood glucose level were more prone to DR than CKD.