Metabolic control and academic achievement over time among adolescents with type 1 diabetes

The relation between metabolic control (HbA1c) and achievement (grade point average [GPA]) was examined over a period of 2.5 years (every 6 months) employing a dynamical systems approach that allowed for the examination of whether HbA1c was associated with change in subsequent GPA and vice versa. Metabolic control tends to deteriorate (i.e., with higher HbA1c reflecting poorer metabolic control) during adolescence. It was hypothesized that these higher levels of HbA1c would limit subsequent increases in GPA. The sample included 252 adolescents (M_{baseline age} = 12.49 years, SD = 1.53; 53.6% female) with Type 1 diabetes. Mothers' report and school records provided information on relevant demographics and GPA; medical records provided values of HbA1c. Two simultaneous coupled change equations (i.e., examining current values in 1 variable associated with changes in the other) controlling relevant risk indicators (i.e., age, sex, disease duration, insulin delivery method, IQ) revealed higher levels of HbA1c limited increases in GPA. Higher levels of GPA, however, were not associated with change in HbA1c except for 2 instances where moderation existed by disease duration and IQ. Higher GPA was associated with slower increases in HbA1c over time for youth with shorter disease duration and lower IQ. These results affirm the importance of maintaining good metabolic control to facilitate adequate school performance across the adolescent years. Further, the results suggest that factors related to school achievement may protect adolescents who are newly diagnosed or who have low cognitive ability from subsequent deterioration in metabolic control.