HbA1c tracking and bio-psychosocial determinants of glycaemic control in children and adolescents with type 1 diabetes: retrospective cohort study and multilevel analysis

Objectives: To explore the association between HbA1c 6 months after diagnosis (6 m-HbA1c) and long-term glycaemic control in children with type 1 diabetes, accounting for other bio-psychosocial determinants.

Methods: This retrospective cohort study, included 155 children (≤16 yr) from the North of Scotland, diagnosed between January 1993 and August 2011, and receiving care between November 2008 and August 2012. Multilevel analysis explored the relationships between 6 m-HbA1c, other persistent or dynamic variables, and HbA1c. Patterns of glycaemic control were identified by cluster-analysis.

Results: 6 m-HbA1c was positively associated with diabetic ketoacidosis at diagnosis, shorter duration of partial-remission, female gender, and psychosocial adversity. In multilevel analysis the effects of 6 m-HbA1c on subsequent HbA1c trajectories remained significant after adjusting for patient- and observation-level predictors. An increase in 6 m-HbA1c of 10 mmol/mol (0.9%) was associated with an average increase in HbA1c levels of 5.3 (95% CI: 4.5-6.2) mmol/mol, or 0.48% (0.41 to 0.57%; p < 0.001) over the follow-up period. Coefficients for linear and quadratic growth identified sustained effects of 6 m-HbA1c on glycaemic control (p < 0.001). Higher average levels or accelerated increases in HbA1c were associated with age at diagnosis, falling BMI (in girls > boys), mental health diagnosis, major adverse life-events, single-parenting, child welfare concerns, neighbourhood deprivation, and clinic non-attendance. Cluster-analysis identified groups with poor or deteriorating control, characterized by older age at diagnosis, multiple psychosocial adversities, and maladaptive healthcare use.

Conclusion: Early HbA1c predicted future glycaemic control across childhood. Trajectories were further modified by biological factors, exposures to psychosocial adversity, and healthcare use.