Gestational diabetes insipidus is a rare, but well recognized, complication of pregnancy. It is related to excess vasopressinase enzyme activity which is metabolized in the liver. A high index of suspicion of gestational diabetes insipidus is required in a correct clinical setting especially in the presence of other risk factors such as preeclampsia, HELLP syndrome, and twin pregnancies. We are presenting a case of gestational diabetes insipidus in a patient with HELLP syndrome. The newborn in this case also had hypernatremia thereby raising possibilities of vasopressinase crossing the placenta.