A nation-wide cross-sectional study of glycosylated haemoglobin in Danish children with type 1 diabetes. 
A nation-wide screening for HbA1c was carried out in Denmark.  Twenty-one paediatric departments treating children with Type 1 diabetes participated.  During a period of 4 months 884 children were included, 93% of all those followed at these centres, representing approximately 70-80% of all children and adolescents with Type 1 diabetes in Denmark.  Among the children 351 were less than or equal to 12 years and 533 were adolescents between 12 and 18 years.  Children less than or equal to 12 years had a HbA1c concentration of 8.9 +/- 1.5 (+/- SD)% and an insulin dose of 0.71 +/- 0.3 U kg-1 24-h-1.  For adolescents HbA1c was significantly higher 9.7 +/- 2.0% (p less than 0.001) and insulin dose significantly increased 0.85 +/- 0.3 U kg-1 24-h-1 (p less than 0.001).  Normal range for HbA1c is 4.0-6.5 (mean 5.3)% of total haemoglobin.  Boys and girls less than or equal to 12 years had similar HbA1c, but girls received 13% more insulin (p less than 0.001).  In the group of adolescents, girls had a HbA1c 4% higher than boys (9.9 +/- 2.0 vs 9.5 +/- 2.0%, p less than 0.025), received 11% more insulin (p less than 0.001), and had 6% higher body mass index (p less than 0.001).  A weak correlation was found between insulin dose and the HbA1c level (r = 0.29, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)