Distribution of Glycated Haemoglobin According to Early-Life and Contemporary Characteristics in Adolescents and Adults without Diabetes: The 1982 and 1993 Pelotas Birth Cohorts

AIM: Glycated haemoglobin (HbA(1c)), a marker of glucose control in individuals with diabetes mellitus, is also related with the incidence of cardiometabolic risk in populations free of disease. The aim of this study was to describe the distribution of HbA(1c) levels according to early-life and contemporary factors in adolescents and adults without diabetes mellitus. METHODS: HbA(1c) was measured in adults aged 30 years and adolescents aged 18 years who are participants in the 1982 and 1993 Pelotas Birth Cohorts, respectively. Bivariate and multivariate analyses were performed to describe the HbA(1c) mean values according to early-life and contemporary characteristics collected prospectively since birth. RESULTS: The distribution of the HbA(1c) was approximately normal in both cohorts, with a mean (SD) 5.10% (0.43) in the 1982 cohort, and 4.89% (0.50) in the 1993 cohort. HbA(1c) mean levels were significantly higher in individuals self-reported as black/brown skin color compared to those self-reported as white in both cohorts. Parental history of diabetes was associated with higher HbA(1c) mean in adults, while stunting at one year old presented an inverse relation with the outcome in adolescents. No other early and contemporary factors were associated with HbA(1c) levels in adults or adolescents. CONCLUSIONS: We found a consistent relationship between HbA(1c) and skin color in both cohorts. Further research is needed to understand the role of genomic ancestry on levels of HbA(1c) concentrations which may inform policies and preventive actions for diabetes mellitus and cardiometabolic risk.