Dopamine Agonists as a Novel "Cure" for Autoimmune Diabetes

We present a patient who, when treated for macroprolactinoma with a dopamine agonist (DA), was able to stop insulin treatment of his autoimmune diabetes for 2 years. The patient was diagnosed with autoimmune diabetes after presenting to emergency services in diabetic ketoacidosis aged 50 years. On presentation, he had high titers of autoantibodies associated with pancreatic islet cell destruction and a high level of glycated hemoglobin. On review in the endocrinology clinic, he displayed signs and symptoms of hypogonadism. Subsequent investigations revealed low testosterone and high prolactin with a pituitary macroadenoma on magnetic resonance imaging. He was diagnosed with a macroprolactinoma and treated with DA. This treatment reversed his insulin requirement and he achieved excellent glycemic control without any hypoglycemic agent. At this point, his diagnosis was revised to latent autoimmune diabetes of adults. Two years after commencing the DA, insulin had to be restarted. We hypothesize that in addition to autoimmune destruction of the pancreatic β cells, there were several other causes of hyperglycemia in this patient, including hyperprolactinemia and hypogonadism. The correct diagnosis led to significant weight loss and appropriate therapy, with a dramatic improvement in quality of life.