Therapeutic challenge: Unusual coexistence of idiopathic central diabetes insipidus and diabetes mellitus in a male with vitiligo

Background: Idiopathic central diabetes insipidus (DI) is a rare endocrine disorder that results from total or partial deficiency of vasopressin secretion. It is idiopathic when the cause is unknown, but in many cases, is associated with autoimmune disorders. Case presentation: We present the case of a 44-year-old male with vitiligo and a family history of diabetes mellitus and thyroid disease. The patient presented with polydipsia and polyuria greater than 8 L/day. After water deprivation test, the patient was diagnosed with partial central diabetes insipidus. Contrast-enhanced pituitary magnetic resonance imaging showed decreased brightness of the neurohypophysis and normal thickness of the pituitary stalk. Because desmopressin was not initially available, the patient was managed with chlorpropamide, carbamazepine, and hydrochlorothiazide, and afterwards substituted. During his outpatient checkups, he presented many episodes of polyuria, the last after 13 years, with polyuria of up to 15 L associated with weight loss, and abnormal blood glucose levels; anti-GAD 65 and IA-2 antibodies were negative. He was subsequently diagnosed with diabetes mellitus and received metformin and insulin; this latter was suspended in subsequent check-ups due to hypoglycemic episodes. Conclusion: We highlight the importance of treatment and adequate control of these pathologies, since they share similar clinical manifestations, can easily have electrolyte imbalance and represent a challenge for endocrinologists and internists.