Correlation Between Glycemic Control (HbA1c), Lipid Profile, and Atherogenic Risk Indices in Children and Adolescents with Type 1 Diabetes Mellitus in Bihor County, Romania: A Retrospective Cross-Sectional Study

Background/Objectives: Dyslipidemia is a frequent metabolic complication in children and adolescents with type 1 diabetes mellitus and is closely linked to the quality of glycemic control and long-term cardiovascular risk. To evaluate the relationship between glycated hemoglobin (HbA1c) and lipid profile parameters (total cholesterol, HDL, LDL, VLDL, triglycerides, and total lipids), as well as the derived atherogenic risk indices—Castelli Risk Index I, Castelli Risk Index II, the atherogenic coefficient (AC), and the atherogenic index of plasma (AIP)—in a cohort of diabetic children and adolescents. Methods: Retrospective cross-sectional study on a cohort of 80 patients aged 1–18 years (45 boys and 35 girls). HbA1c, lipid profile values, and derived atherogenic risk indices were analyzed using Pearson and Spearman correlation coefficients, Welch’s t-test, ANOVA/Kruskal–Wallis, Mann–Whitney tests, and comparison across glycemic-control categories. Results: Mean HbA1c of the study population was 11.3 ± 2.7% (100 ± 30 mmol/mol, IFCC), with 76.3% of patients in severe metabolic imbalance (HbA1c ≥ 9%). HbA1c correlated significantly and positively with triglycerides (rho = 0.44; p < 0.001), non-HDL-cholesterol (rho = 0.42; p < 0.001), LDL-cholesterol (rho = 0.35; p = 0.002), and total cholesterol (rho = 0.30; p = 0.009) and negatively with HDL-cholesterol (rho = −0.33; p = 0.004). All four atherogenic indices correlated significantly with HbA1c, the strongest associations being observed for AIP, Castelli Risk Index I, and the atherogenic coefficient (rho = 0.44 for all three; p < 0.001), followed by Castelli Risk Index II (rho = 0.39; p < 0.001). Only 15.5% of patients fell into the high-risk AIP category (>0.21), while 25.7% fell into the high-risk category for both Castelli Index I (≥4.5) and the atherogenic coefficient (≥3.5). Conclusions: These findings are consistent with an association between poorer glycemic control and a less favorable atherogenic lipid profile in children and adolescents with type 1 diabetes. Composite atherogenic indices showed associations with HbA1c comparable in magnitude to those of some individual lipid parameters; their clinical value for cardiovascular risk stratification in pediatric populations remains to be validated.