Peculiarities of diabetes in patients with hyperthyroidism.

The authors report on 5 patients aged 25 to 63, with hyperthyroidism confirmed by high and plateau radioiodine uptake curves, protein-bound iodine of more than 7.4 micrograms/dl and low values of TSH (0.95 +/- 0.7 microU/ml). The fasting blood sugar was 157.6 mg% +/- 41 on average. Glycosuria ranged from 3.8 to 20.7 g/24 h and had a mean of 11 g 8.8 g/24 h. Determination of serum immunoreactive insulin (IRI) revealed very variable values: in one patient it was nondetectable, in 3 patients it had normal values, and in one patient it exceeded 41 microU/ml. These data confirm the authors' earlier reports on the variability of the glycoregulating mechanisms in hyperthyroidism, ranging from diabetes mellitusto hyperinsulinic reaction. However, most of the patients had normal IRI and reduced tolerance to glucose. The latter is probably due to the excess of thyroid hormones.