Glycated haemoglobin variations in paediatric type 1 diabetes: the impact of season, gender and age.

AIM To study whether monthly variations in type 1 diabetes incidence are related to monthly glycated haemoglobin (HbA1c) levels at diagnosis and if high HbA1c at diagnosis is related to certain clinical variables at diagnosis and during the clinical course of the disease. METHODS Data from 4430 boys and 3590 girls registered in the Swedish paediatric diabetes quality registry, Swedish paediatric diabetes quality registry, from 2000 to 2010 were analysed. RESULTS Month of onset varied (p < 0.001), with 53% diagnosed during September to February, and mean HbA1c at diagnosis was highest in May (10.9%, 96 mmol/mol) and lowest in (October 9.4%, 88 mmol/mol) (p < 0.001). Girls showed higher HbA1c at onset than boys (p < 0.001). More than half (53%) with an annual mean HbA1c of >9.3% (78 mmol/mol) and 4% of those with an annual mean of <7.4% (57 mmol/mol) in 2007 had >9.3% (78 mmol/mol) in 2010. CONCLUSION Patients with high HbA1c levels during a certain period have the same high levels several years later. This group, perhaps including those with high HbA1c level at diagnosis, may need more intensive care, including extra support from the diabetes teams and other forms of medical treatment.