Distinguish between diabetes insipidus and diabetes mellitus.

Explanation

a) Diabetes insipidus: Deficiency of vasopressin causes diabetes insipidus in which the patient excretes large volumes of urine, resulting in dehydration and thirst.
b) Diabetes mellitus : A condition resulting from lack of insulin as a result of which the body cannot store or oxidise sugar efficiently (and sugar is lost through urine).