The reliable biomarkers are essential for enhancing the diagnosis and monitoring of pediatric type 1 diabetes mellitus (T1DM), while the clinical spectrum of circulating microRNAs (miRNAs) depfigends on the accurate normalization with reference to genes. The study assessed the expression and diagnostic ability of circulating miR-1 and miR-155 in 70 children with T1DM (9.8 ± 2.7 years; 40 males and 30 females) and 30 healthy cases matched for age and sex from Kirkuk, Iraq. We extracted serum RNA using a modified TRIzol protocol. MiRNA expression was measured by stem-loop quantitative real-time PCR (qPCR), normalized to miR-423 and U6 small nuclear RNA. Stability of expression was assessed on the coefficient of variation, while diagnostic performance was evaluated using a ROC curve analysis and stratification on HbA1c. Although miR-423 showed less variability (CV = 1.76%), U6 normalization was more accurate. In T1DM patients, miR-1 was significantly overexpressed with a fold change of up to 15.6 and discriminative performance (AUC 0.838; sensitivity 70%; specificity 87.5%). In addition, poor glycemic control is strongly associated with miR-1 expression (p < 0.0001). Conversely, miR-155 presented varying expression patterns. Normalized circulating miR-1 relative to U6 can be a potential biomarker for T1DM risk in children.
