Circulating Omentin-1 Across BMI Categories in Type 2 Diabetes and its Association with Insulin Resistance: A Cross-Sectional Study from South India

Abstract Introduction: Omentin-1 is an adipocytokine predominantly secreted by visceral adipose tissue and associated with insulin sensitivity. Altered levels of omentin-1 in type 2 diabetes mellitus (T2DM) and obesity denote a potential link with insulin resistance. Methods: Two hundred twenty-five adult males with T2DM were segregated into non-obese ( n = 75), overweight ( n = 75), and obese ( n = 75) groups. Anthropometric, haemodynamic, and biochemical parameters, including glucose, insulin, lipid profile, and omentin-1 were measured. Insulin resistance was assessed using validated surrogate indices. Group comparisons were performed and associations were examined using correlation analysis and a prespecified multivariable linear regression model. Results: Obese subjects had higher BMI, waist-to-hip ratio, fasting glucose, HbA1c, fasting insulin, HOMA-IR, lipid fractions, and METS-IR as compared to non-obese. Serum omentin-1 levels declined progressively with increasing adiposity non-obese 687.6 (654.1–763.2), overweight 587.6 (548.6–658.1), obese 459.3 (398.7–524.8) ng/L; P < 0.001. Omentin-1 showed inverse correlations with BMI (γ = −0.703), waist-to-hip ratio (γ = −0.717), HOMA-IR (γ = −0.403), triglyceride-BMI index (γ = −0.695), and LDL-cholesterol (γ = −0.417), and a positive correlation with QUICKI (γ =0.403; all P < 0.001). In the multivariable model, LDL-cholesterol remained independently associated with circulating omentin-1 levels (β =2.527, P = 0.043). Conclusion: Serum omentin-1 shows an inverse association with adiposity, insulin resistance, and lipid parameters in T2DM, suggesting that omentin-1 could serve as a potential marker of an adverse cardiometabolic profile, although comprehensive studies are further warranted.