Subclinical thyroid hormone abnormalities in type I diabetic children and adolescents. Relationship to metabolic control.

The serum levels of thyroid hormones and thyroid stimulating hormone were compared in 64 type I diabetic children and adolescents without ketosis and in 28 age matched normal subjects. Only T3 levels were significantly different in the diabetic patients (2.38 +/- 0.41 nmol/l) than in controls (2.64 +/- 0.52 nmol/l) (p less than 0.01) confirming the existence of the 'low T3 syndrome' in diabetic children. A negative correlation was found between T3 and blood glucose as well as glycosylated haemoglobin suggesting that short-term hyperglycaemia could regulate T3 concentration. Thyroid function was not different in diabetic children with or without thyroid antibodies. We conclude that serum T3 level is influenced by the degree of metabolic control and that thyroid function in diabetic children should be assessed by the measurement of the serum concentration of T4, FT4 and TSH.