An Assessment of Serum Irisin and Intercellular Adhesion Molecule-1 as Potential Indicators of Retinopathy in Type 2 Diabetes Mellitus

Background: Diabetic retinopathy (DR) impairs retinal function and causes significant vision loss. Irisin has been recently implicated in the pathogenesis of DR. Intercellular adhesion molecule-1 (ICAM-1) is a cell surface glycoprotein that primarily facilitates leucocyte recruitment from circulation to inflammation sites. Aims: This cross-sectional study aimed to explore the significance of circulatory irisin and ICAM-1 levels in DR. Subjects and Methods: This cross-sectional analytical study was conducted at a tertiary care hospital in Puducherry, India. Type 2 diabetes mellitus (T2DM) patients with retinopathy ( n = 60) and without retinopathy ( n = 60) were recruited. Apart from anthropometric data, blood samples were collected for routine biochemical tests and estimation of serum irisin and ICAM-1 by ELISA. Data were analysed using IBM SPSS version 20.0. The variables were compared using Independent Student’s- t -test, Mann–Whitney U -test, one-way analysis of variance, or Chi-square test. Receiver operator curve (ROC) analysis evaluated irisin and ICAM-1 in differentiating proliferative DR (PDR) and non-proliferative DR (NPDR). Results: Compared to T2DM patients without DR, Serum irisin was higher in those with DR, but no difference was observed in ICAM-1 between the 2 groups. Both irisin and ICAM-1 were decreased in vision-threatening DR (VTDR) compared to non-vision-threatening DR (non-VTDR). Decreased levels of irisin ( P = 0.84) and ICAM-1 ( P ≤ 0.001) were seen across DR stages. ROC analysis showed irisin differentiated NPDR and PDR (AUC = 0.7, P = 0.01). Conclusions: Serum irisin and ICAM-1 increased in earlier stages of DR but decreased in later stages. They were decreased in pre-proliferative and proliferative stages of DR, suggesting roles in leucocyte migration and angiogenesis. Clinical management may have contributed, and further research is needed.