The role of adiponectin in diabetic retinopathy and insulin resistance

Diabetic retinopathy (DR) is a common microvascular complication of type 2 diabetes mellitus (T2DM). The pathogenesis of DR is multifactorial, involving chronic hyperglycemia, oxidative stress, inflammation, and insulin resistance (IR), all of which contribute to microvascular damage in the retina. This study aimed to evaluate the role of adiponectin (APN) in DR and its correlation with IR, inflammatory, and glycemic control. A total of 100 T2DM patients were enrolled and equally divided into two groups based on the presence or absence of DR. Demographic characteristics, glycemic indices, IR, inflammatory markers, and serum APN levels were analyzed. The diagnostic performance of APN was assessed using receiver operating characteristic (ROC) curve analysis. Patients with DR had a significantly longer duration of diabetes compared to those without DR (p<0.001). Biochemically, the DR group showed significantly higher levels of fasting blood sugar (p=0.025), hemoglobin A1C (p=0.003), fasting insulin (p=0.005), homeostatic model assessment for IR (p=0.001), and C-reactive protein (p<0.001). Conversely, the median serum APN levels were significantly lower in DR patients (median: 2.65 ng/mL) than in those without DR (median: 5.36 ng/mL; p<0.001). ROC analysis revealed that APN had a fair diagnostic performance for detecting DR (area under the curve: 0.773, 95% confidence interval: 0.679-0.867, p<0.001). DR is associated with poor glycemic control, increased IR, elevated inflammatory markers, and reduced serum APN levels. APN may serve as a potential biomarker for the detection and risk stratification of DR in T2DM patients.