Type 2 Diabetes Mellitus: A Growing Lifestyle Disorder Among Young Adults

Central diabetes insipidus is a rare disorder of the hypothalamus and posterior pituitary gland. It is uncommon in patients with type 2 diabetes mellitus, and both conditions can present with similar symptoms such as excessive thirst and increased urination. Because of this overlap, polyuria is often wrongly attributed only to poor glycemic control. We report the case of a 65-year-old female with known type 2 diabetes mellitus and inadequate blood sugar control, who presented with long-standing excessive urination. Laboratory investigations showed hypernatremia, increased plasma osmolality, and low urine osmolality, suggesting diabetes insipidus. A water deprivation test followed by subcutaneous desmopressin administration was performed, which showed a clear improvement in urine concentration, confirming central diabetes insipidus. Magnetic resonance imaging of the brain revealed a normal posterior pituitary bright spot, suggesting an idiopathic cause. This case emphasizes that persistent polyuria in diabetic patients should not always be attributed to uncontrolled diabetes mellitus, and other conditions such as diabetes insipidus should also be considered.