Hypothyroidism Could be a Potential Factor to Prolong Subcutaneous Nodules of Exenatide once Weekly: A Case Report

ABSTRACT Objective: Exenatide once weekly (ExeOW) is one of the long-acting glucagon-like peptide 1 receptor agonists. Embedding exenatide in poly(D,L-lactide-co-glycolide) microspheres enables the once-weekly subcutaneous injection of exenatide as a treatment for diabetes. We report a case of a patient with type 2 diabetes and hypothyroidism who developed long-standing subcutaneous nodules after treatment by ExeOW injection. Methods: Case report and review of the literature. A 57-year-old Japanese man with type 2 diabetes treated with ExeOW and primary hypothyroidism. Results: We observed multiple subcutaneous nodules remaining at the ExeOW injection site for >10 weeks. As the patient's thyroid hormone levels normalized, these nodules decreased and disappeared, and his hemoglobin A1c levels improved. Conclusion: The patient's clinical course suggests that the hydrolysis of ExeOW at the site of injection may be inhibited by concomitant hypothyroidism, in which glycosaminoglycans including hyaluronic acid are known to accumulate (including in the skin). This case may indicate that hypothyroidism prolongs the existence of subcutaneous nodules from ExeOW treatment. Abbreviations: ExeOW = exenatide once weekly GLP-1 = glucagon-like peptide 1 HbA1c = hemoglobin A1c NGSP = National Glycohemoglobin Standardization Program PLG = poly(D,L-lactide-co-glycolide)