Background/Objectives: Type 1 diabetes mellitus (T1DM) is a common chronic disease of childhood, with a rising incidence worldwide, across Europe, and in Romania. This retrospective, descriptive, single-centre study aimed to describe the demographic features, the temporal distribution and the approximate incidence of T1DM in children diagnosed in Bihor County, Romania. Methods: Of 174 children with newly diagnosed T1DM at Emergency Clinical County Hospital Bihor (2014–2024), 172 residing in Bihor County were analysed (two were excluded because they resided outside the county; none was excluded for missing data) for sex, age at onset, residence, and year and month of onset. The incidence was approximated using an assumed pediatric population (83,000–105,000 children aged 0–17 years), and the findings were set against official administrative registry data (INSP-CNSSP) for Bihor County and Romania. Results: The sex ratio was close to unity (47.1% girls; 95% confidence interval (CI) 39.8–54.5%). The rural share of cases (45.3%) did not differ significantly from the rural share of the county’s general all-ages population in the 2021 census (52.7%; p = 0.054), a non-age-matched comparison that should be interpreted cautiously. Mean age at onset was 9.2 ± 4.5 years (girls 9.7 ± 4.3, boys 8.7 ± 4.6 years; p = 0.135); the largest proportion of cases (37.8%) was observed at ages 10–14 years. The annual number of recorded new cases ranged from 11 to 23 without a statistically significant temporal trend (Poisson regression of case counts, without population offset, p = 0.185; rate ratio 1.27 for 2019–2024 versus 2014–2018, 95% CI 0.93–1.76, p = 0.126). The approximate crude incidence was 14.9–18.8 cases per 100,000 children/year (point estimate 16.6); this is an indicative estimate that is not directly comparable with national estimates for children aged 0–14 years. Administrative registry data (INSP-CNSSP), which cover all forms of diabetes and children in active follow-up, showed an increase in the number of children aged 0–14 years in follow-up from 32 (2012) to 187 (2021) and prevalence above the national average, but cannot confirm trends in pediatric T1DM incidence or prevalence. Conclusions: This descriptive single-centre series broadly followed national and European patterns in sex ratio, age distribution and seasonality, with a relatively stable number of recorded annual cases. Given the single-centre case ascertainment and approximate denominators, the findings should not be regarded as population-based incidence estimates or as evidence of a higher local incidence or burden of T1DM; confirmation through multi-source case ascertainment or registry linkage is needed.

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.