Aims: To determine whether intra-individual measures of diabetes control deteriorated through adolescence and whether HbA1c in late childhood was predictive of HbA1c after adolescence.
Methods: Retrospective analysis of sequential 3-6 monthly data including HbA1c, height, weight, and total daily insulin dosage in 118 patients with Type 1 diabetes aged between 8.00 and 17.99 years between 1983 and 1999.
Results: In females mean body mass index (BMI) increased sharply during adolescence but there was no significant increase in males. The mean total daily dose of insulin/weight (TDDI/W) increased sharply for females through puberty. Males exhibited a constant rate of increase in mean TDDI/W from pre- to post-puberty. There was a constant increase in mean HbA1c for females, with an estimated increase from pre- to post-puberty of 0.92%. In males there was only a slight increase from pre- to peri-puberty and no change subsequently. Comparing pre-puberty (8-9.99 years) and post-puberty (15-17.99 years) in the total group, 47% of patients remained in the same mean HbA1c grouping, 37% had worsened control and 16% had improved control. Analysis of change in the absolute value of mean HbA1c showed that the majority of patients had mean HbA1c values that remained within +/- 1% (54%) or +/- 2% (82%) from pre- to post-puberty. A significant proportion showed significantly worsening control with only a minority showing improved metabolic control from pre- to post-puberty.
Conclusions: The likelihood of a significant improvement in HbA1c from late childhood to adolescence is remote, with the majority of patients having either constant or deteriorating metabolic control.