n type 1 diabetes, the importance of metabolic control for the development of micro- and macrovascular complications is wellrecognized,despite other confounders, metabolic control is established as the main factor for diabetes outcome. As prevention of type1,2 and glycated hemoglobin A1c (HbA1c) strongly correlates with the risk of coronary heart disease.3 Therefore,
1 diabetes is currently not available and diabetes duration is not modifiable, the identification of additional contributors for diabetes outcome is important. Improvement of long-term metabolic control is of major interest in young patients with type 1 diabetes.4-6 Hormonal changes during puberty7-9 are known to lead to poor metabolic control. Alterations of the growth hormone/
insulin-like growth factor-1 axis10 and abnormalities of ovarian function in girls11 may contribute to insulin resistance.
However, higher HbA1c levels during puberty are not only explainable by demographic and treatment factors, reduced
compliance because of psychosocial difficulties, and by hormonal changes during puberty; factors tracking from disease onset
onward seem to play an important role in metabolic diabetes outcome.
Although the phenomenon of ‘tracking’ has already been described in other conditions, for example blood pressure and body
mass index (BMI),12 tracking of metabolic control has rarely been investigated. A
retrospective analysis carried out in the Oxford area assumed that within an overall improvement in HbA1c, persistent individual tracking does exist.13
In the present study, therefore, we explore the tracking of HbA1c, representing
metabolic control within the first decades of diabetes. We test this hypothesis in a
multicenter setting, following HbA1c levels in a set of patients with type 1 diabetes from disease onset in childhood (younger than 12 years of age) through
prepuberty and puberty until young adulthood.