Circulating iodothyronines in juvenile diabetic outpatients.

Serum T3, rT3, T4 and TSH were measured in ten healthy subjects, in nine juvenile diabetic outpatients in fair metabolic control (fasting plasma glucose 6.5 mmol/1, 2.6-9.5 mmol/1 (mean, range), HbA1 10.1%, 8.1-12.2%), and in ten juvenile diabetic outpatients in poor metabolic control but without ketonuria (fasting blood glucose 15.1 mmol/l, 11.1-22.4 mmol/l, HbA1, 13,8% 10.8-16,2%. Serum T3 was identical in normal subjects and in diabetics in fair metabolic control. Diabetics in poor metabolic control had 13.0% lower serum T3 than normal subjects (2 p less than 0.05). No difference between groups was observed in serum rT3, T4 and TSH. These findings indicate that in diabetic patients, metabolic derangement induces alterations in serum T3 more easily than in serum rT3. However, alteration in serum T3 is not a sensitive indicator of moderate metabolic derangement in diabetic patients.