Endocrine Abstracts

Background and aims: Incretin mimetics are a new class of pharmacological agents with antihyperglycemic actions that mimic the actions of incretin hormones originating in the gut, such as glucagon-like peptide (GLP)-1. The thyroid gland exhibit a strong GLP-1 receptor expression in rodents but only low receptor levels in humans. GLP-1 receptors activation stimulates calcitonin secretion and promotes the development of C cell hyperplasia and medullary thyroid cancer in rodents. We have monitored the thyroid function in diabetic patients in treatment with exenatide.

Materials and methods: Thirty-three patients with type 2 diabetes mellitus were recruited for this study. The subjects were between 40 and 64 years. Patients were screened initially with a questionnaire detailing their medical history, hereditary or familial medullary thyroid carcinoma. The level of serum TSH, calcium and calcitonin in the blood were measured. Neck ultrasound was performed. The patients followed therapy 24 months with exenatide (10 μg injected s.c. twice daily, 60 min before breakfast or dinner).

Results: Baseline characteristics of subjects: 23 patients were not diagnosed with thyroid disease, 8 patients present nontoxic goiter, and 2 patients Hashimoto’s thyroiditis. Median value of TSH was 3.39 μIU/ml of calcitonin 8.62±1.24 ng/l, of total calcium 9.08±0.32 mg/dl, and of ionized calcium 4.52±0.22 mg/dl. The level of TSH, calcium and calcitonin was similar before and after 24 months with exenatide treatment in patients with type 2 diabetes. The nodules remain stable in size.

Conclusion: The clinical study with exenatide has not revealed an increase in calcitonin levels during treatment. The surveillance of thyroid nodules is indicated. The study limit of low numbers of patients, requires further validation.