Metabolic hormones and adipokines as mediators of obesity-induced insulin resistance

Background. Obesity is a complex metabolic disorder strongly associated with insulin resistance, a key factor in the development of type 2 diabetes mellitus and cardiovascular diseases. The purpose of this study is to evaluate the levels of key metabolic hormones and adipokines in obese individuals and investigate their role as mediators in the development of insulin resistance compared to healthy controls. Materials and methods. This case-control study was conducted in Samarra, Iraq (January-April 2024) on 55 obese males and 35 healthy male controls. Inclusion required body mass index (BMI) ≥ 30 kg/m2 for cases and 18.5–24.9 kg/m2 for controls, excluding chronic diseases. After ethical approval and consent, fasting blood samples (10 mL) were collected, centrifuged, and stored at –20 °C. Serum levels of adipokines, insulin, and metabolic markers were measured using enzyme-linked immunosorbent assay. Results. The study revealed significant differences (p ≤ 0.05) between obese and control groups in BMI and lipid profiles, with higher BMI, total cholesterol, triglycerides, low-density lipoprotein, and very-low-density lipoprotein, and lower protective high-density lipoprotein in obese individuals, indicating disrupted lipid metabolism and increased cardiovascular risk. Glycemic control markers (fasting blood glucose, glycated hemoglobin, insulin, HOMA-IR) were elevated in obesity, while quantitative insulin sensitivity check index decreased, confirming insulin resistance. Inflammatory markers (asprosin, plasminogen activator inhibitor-1, fibrinogen, calprotectin, lipocalin-2, resistin) were higher, whereas neuregulin-4 and ghrelin were lower, reflecting hormonal and inflammatory dysregulation linked to obesity. Conclusions. Obesity induces insulin resistance through hormonal and inflammatory imbalances, including elevated adipokines and metabolic hormones that disrupt glucose and lipid metabolism. Chronic inflammation and altered hormone levels impair insulin signaling, increasing the risk of metabolic diseases such as type 2 diabetes mellitus and cardiovascular complications.