Circulating microRNA-122 Expression and Serum Fetuin-A Levels in Iraqi Patients with Type 2 Diabetes Mellitus: Associations with Insulin Resistance and Metabolic Disturbances—A Case–Control Study

Abstract Type 2 diabetes mellitus (T2DM) constitutes a significant burden throughout Iraq and the Middle East and North Africa region, where adult diabetes prevalence reached 16.2% in 2021. Circulating microRNA-122 (miR-122) as well as serum fetuin-A are key hepatic biomarkers mechanistically implicated in lipid dysregulation and insulin resistance; however, data pertaining to Iraqi patients remain limited. The aim of this study was to quantify circulating miR-122 and serum fetuin-A in Iraqi T2DM patients versus healthy controls and to characterize their associations with insulin resistance, glycemic control, and lipid metabolism. Ninety T2DM patients and 90 frequency-matched healthy controls were enrolled in this prospective case–control research at the Diabetes and Endocrinology Center in Baghdad between January and September 2025. The American Diabetes Association 2025 criteria (fasting plasma glucose ≥126 mg/dL or glycated hemoglobin [HbA1c] ≥6.5%) were used to confirm T2DM. Participants with nonalcoholic fatty liver disease (NAFLD; fibrosis-4 index >1.30 plus ultrasound), liver disease, renal impairment, or hematological disorders were excluded. Power analysis confirmed n = 90 per group (α = 0.05; power = 0.80; d = 0.60). miR-122 was quantified by Minimum Information for Publication of Quantitative Real-Time PCR Experiments-compliant reverse transcription quantitative polymerase chain reaction with cel-miR-39 spike-in normalization; hemolysis was assessed by the miR-451a/miR-23a ratio. Fetuin-A was measured by sandwich enzyme-linked immunosorbent assay (BioVendor; intra-assay coefficient of variation [CV] < 5.2%). Insulin resistance was estimated as homeostasis model assessment of insulin resistance (HOMA-IR). Continuous data are presented as median (interquartile range [IQR]) and compared by Mann–Whitney's U test. Spearman's correlations were Bonferroni-corrected (α adj = 0.0025). Multivariable logistic regression and receiver operating characteristic curve analysis with 95% confidence intervals (DeLong method) were performed. miR-122 was 4.2-fold higher in T2DM patients (3.14 [IQR 2.28–4.47]) than controls (0.75 [0.52–1.12]; p < 0.001). Serum fetuin-A was 2.3-fold elevated (363.9 [281.4–446.2] vs. 152.7 [138.4–167.1] μg/mL; p < 0.001). Both biomarkers correlated significantly with HOMA-IR, HbA1c, fasting blood glucose, and atherogenic lipid indices after Bonferroni correction. On multivariable analysis, miR-122 (odds ratio = 3.14; 95% CI: 1.87–5.27; p < 0.001) and fetuin-A (OR = 1.009; 95% CI: 1.005–1.013; p < 0.001) were independent predictors of T2DM after adjustment for age, sex, body mass index, and statin use (Nagelkerke R 2 = 0.614). Area under the curve (AUC) was 0.80 (95% CI: 0.74–0.86) for fetuin-A and 0.76 (95% CI: 0.69–0.83) for miR-122; combining both markers did not significantly improve discrimination (p = 0.18) The combined model achieved an AUC of 0.82 (95% CI: 0.76–0.88). Both miR-122 and fetuin-A are significantly elevated in Iraqi T2DM patients and independently associated with insulin resistance and dyslipidemia, even after NAFLD exclusion, suggesting they reflect hepatic metabolic dysfunction in established T2DM. Diagnostic performance was moderate to good but offered limited additive value over standard glycemic markers. Prospective multicenter studies are needed to determine whether these biomarkers can enhance metabolic risk stratification in T2DM.