Distribution and determinants of glycosylated hemoglobin in adolescents - Results from a nationwide population-based survey in Germany.

The role of glycosylated hemoglobin (HbA1c) in youth is largely unclear. The aims of this study are to investigate the distribution and potential determinants of HbA1c among a population-based sample of adolescents. The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) Wave 2 includes a nationwide representative sample of 0-17-year-old participants. For this evaluation, data from a randomly selected subgroup aged 14-17 years and without diagnosed diabetes was included (n = 857). Percentile-based HbA1c values (measured at laboratory in whole blood samples by high performance liquid chromatography) were calculated to examine HbA1c distribution. Multivariable linear regression analyses were performed to investigate factors (age, sex, parental socioeconomic status, body mass index (BMI), birth weight, smoking, alcohol consumption, healthy food diversity, sport activity, oral contraceptive use) associated with HbA1c. The mean HbA1c level was 5.2% (minimum: 3.9%, P10: 4.8%, P50: 5.1%, P90: 5.5%, maximum: 6.7%). Overall, 2.8% of adolescents had an HbA1c value in the prediabetic range (5.7-6.4%) and 0.1% had an undiagnosed diabetes (≥6.5%). Multivariable regression analysis showed an inverse association of age with HbA1c (17 vs. 14 years: ß: -1.18; 95% CI -2.05, -0.31). Higher HbA1c values were observed for higher BMI-standard deviation scores (SDS) (ß: 0.24; 95% CI -0.04, 0.52) and smoking (ß: 0.73; 95% CI -0.12, 1.57), but these tendencies were non-significant. In sex-stratified analysis, smoking and birth weight were significantly associated with HbA1c in boys. Among adolescents without diagnosed diabetes in Germany, HbA1c values ranged from 3.9% to 6.7%. To ensure health in adulthood, the influence of determinants on HbA1c levels in younger age should be further investigated.