Trajectories of hemoglobin A1c and body mass index z-score over four decades among 2 to 18 year olds with type 1 diabetes.

OBJECTIVES: To determine trajectories of glycemic control and body mass index (BMI) z-score in a large pediatric sample with type 1 diabetes (T1D) over a 38-year period, and to evaluate sex differences and temporal changes in the prevalence of these trajectories.
METHODS: We conducted a longitudinal, retrospective study of 7002 2 to 18 year olds with T1D followed between 1978 and 2016 at a single center. Group-based modeling was used to identify trajectories for hemoglobin A1c (HbA1c) and BMI z-score. Multinomial logistic regression identified predictors of membership to less favorable glycemic trajectories.
RESULTS: Group-based modeling yielded 5 HbA1c trajectories. A total of 86% of the sample fell within 3 trajectories that were largely stable across childhood and adolescence, and 14% fell within 2 trajectories characterized by marked deterioration beginning in pre-adolescence. Girls were more likely to be in the HbA1c trajectory with the highest starting HbA1c and significant deterioration during adolescence, and in the highest two BMI z-score trajectories. Patients with non-white race had the highest odds of belonging to a less favorable HbA1c trajectory. Prevalence of the high stable HbA1c trajectory decreased and prevalence of the low stable HbA1c trajectory increased over the study period.
CONCLUSIONS: A minority of youth with T1D experienced deterioration of glycemic control during adolescence. Girls were more likely to belong to the worst HbA1c trajectory and to BMI z-score trajectories in the overweight/obese range, which may increase cardiometabolic risk. Addressing racial/ethnic disparities in glycemic control should remain a priority. Advances in T1D management correlated with favorable shifts in HbA1c trajectory prevalence.