Serum Level and Genetic Polymorphism of Interleukin-33 in Iraqi Patients with Type 2 Diabetes Mellitus

Background: Type 2 diabetes mellitus (T2DM) is characterized by insulin deficiency and resistance. This study evaluated serum interleukin‑33 (IL‑33) and its soluble receptor (sST2), plus two IL‑33 gene polymorphisms (rs7044343, rs1929992), for association with T2DM in Iraqi patients. Patients and Methods: In this case–control study, 120 T2DM patients and 80 age and sex matched healthy controls were used. Fasting blood glucose and glycated hemoglobin (HbA1c) confirmed diabetic status. Serum IL 33 and sST2 concentrations were measured by ELISA. Genotyping of IL 33 rs7044343 and rs1929992 was performed via PCR–RFLP. Allele and genotype frequencies were compared using χ² tests; associations were expressed as odds ratios (ORs) with 95% confidence intervals (CIs). Statistical significance was set at p < 0.05. Results: Compared to controls, T2DM patients showed significantly higher serum IL 33 (mean ± SD: 43.2 ± 12.7 vs 28.5 ± 9.3 pg/mL, p < 0.001) and sST2 (56.8 ± 14.1 vs 34.7 ± 10.5 ng/mL, p < 0.001). The IL 33 rs1929992 variant exhibited no significant difference between groups (p = 0.30). In contrast, the rs7044343 AA genotype was more frequent in T2DM patients than controls (AA = 34% vs 18%; OR = 2.35, 95% CI 1.22–4.52, p = 0.010), while the CC genotype conferred a protective effect (CC = 22% vs 38%; OR = 0.48, 95% CI 0.26–0.89, p = 0.018). Conclusion: Elevated IL 33 and sST2 levels, together with the rs7044343 AA genotype, are associated with increased susceptibility to T2DM in Iraqi patients. These findings support IL 33 pathway involvement in T2DM pathogenesis. Keywords: IL-33, T2DM, Lipid profile, ST2 receptor.