[Changes in the thyroid hormone picture that may be found in severely decompensated type II diabetics]

Thyroid hormone picture of 28 patients (15 males and 13 females), mean age 56.6 yr (range 45-65 yr), with seriously decompensated type II diabetes mellitus has been studied. In each patient the study was repeated after 3 months of treatment of diabetes. The patients showed significantly lower serum T3 levels and significantly higher serum rT3 levels (P less than 0.001), in comparison with a group of 16 normoglicemic subjects. After 3 months of strict control of diabetes T3 and FT3 significantly increased (P less than 0.01), whereas significant variations of rT3 were not found. Among the whole group of diabetics 5 patients had low levels of serum T4 (P less than 0.01 vs. controls), high levels of serum TSH (P less than 0.001 vs. controls) and an exaggerated responsiveness to exogenous TRH (P less than 0.001 vs. controls). After the 3 months of treatment these patients showed a significant decrease of rT3 (P less than 0.02) and of delta-TSH (P less than 0.01). In the whole group of diabetics significant statistical correlations between glycometabolic and thyroid parameters were not found. The study, on the whole, showed in patients with seriously decompensated type II diabetes, a hormone picture like the low-T3 syndrome, in some cases, however, pituitary TSH secretion suggested the existence of incipient failure of thyroid hormones. A connection between alterations in thyroid hormone picture and glycometabolic imbalance, even statistically labile, is however indicated by improvement of thyroid function when diabetes is carefully controlled.