The combined effect of hypomagnesemia and hypokalemia inducing nephrogenic diabetes insipidus in a patient with type 1 diabetes mellitus.

Nephrogenic diabetes insipidus (NDI) is rarely considered against more common differentials such as diabetes mellitus in patients presenting with polydipsia and polyuria. Hypokalemia and hypercalcemia are known to induce NDI, but not much is known about hypomagnesemia. Hypokalemia refractory to therapy should prompt consideration of hypomagnesemia.