Height and weight were measured in young patients with type 1 diabetes up to the age of 22 y. We found no difference between birth length standard deviation scores (SDS), final height SDS and target height SDS. The study group of 89 diabetic boys and girls did not differ in final height from age- and sex-matched healthy controls. SDS for height at diagnosis, +0.17 +/- 1.10, exceeded that for final height, -0.06 +/- 0.97 (p = 0.037). Height SDS decreased between the ages of 11 and 18 (p < 0.01). In diabetic girls, but not boys, final height SDS was significantly related to mean HbA1c during puberty (r = -0.40; p = 0.025). Weight gain occurred from age of menarche in girls with type 1 diabetes. At the age of 18, diabetic girls were 6.5 kg heavier and had 2.7 kg/m2 higher body mass index (BMI) than control girls (p < 0.001). Diabetic boys were not heavier than control boys. There was a significant relationship between mean HbA1c during puberty and BMI at the age of 18 in diabetic girls (r = 0.47; p = 0.009). In diabetic females, body weight remained unchanged, HbA1c improved and the dose of insulin was significantly reduced between 18 and 22 y of age. The HbA1c improvement was most marked in patients with poor metabolic control. In conclusion, although mean final height was normal in young patients with type 1 diabetes, growth was increased before diagnosis and pubertal growth spurt was reduced. Adolescent overweight was overrepresented; it related to poor metabolic control in females with diabetes, but showed no further acceleration in early adulthood.