Introduction
Nephrogenic diabetes insipidus (NDI) is a significantly rarer condition than diabetes mellitus (DM). Both forms of diabetes (DI and DM) can be difficult to distinguish if they were to occur simultaneously as both present similarly, with polydipsia and polyuria. NDI results from the failure of the kidney to concentrate urine due to the insensitivity of the distal nephron to respond to antidiuretic hormone (ADH), also known as arginine vasopressin (AVP). This leads to polyuria of more than 3L in 24 hours with a urinary osmolality of less than 300 mOsm/kg H2O and specific gravity of less than 1.005, causing an increase in plasma osmolality in response to raised serum sodium and urea.(1,2) NDI can be hereditary or an acquired disorder. Acquired NDI is commonly caused by drugs such as lithium or metabolic imbalances, such as hypokalaemia and hypercalcemia.(3) Refractory hypokalaemia management has been attributed to hypomagnesaemia. The co-administration of magnesium and potassium is essential for correcting persistent hypokalaemia.(4) Here we describe a case of a type 1 diabetic who acquired NDI due to hypokalaemia and hypomagnesemia.