It is a rare type of diabetes with common symptoms as frequent excretion of very diluted urine, unusual thirst patterns and dehydration. Although the traits are common to diabetes mellitus – which is caused by deficiency of insulin and blood sugar levels; Diabetes Insipidus is a completely unrelated form of diabetes.
Diabetes Insipidus or DI, as it is often called, occurs when there is a disruption of the complex system that regulates fluids within the body. Fluid regulation is very important to the health, which oversees thirst control and the functioning of the kidneys using Antidiuretic hormones (ADH). Diabetes Insipidus hinders proper functionality of this overly delicate system.
There are mainly four types of DI:

Nephrogenic DI:

It occurs when the kidneys stop responding to the ADH normally. It may have caused by chronic disorders such as kidney failure or polycystic kidney disease.

Neurogenic DI:

One of the most common types of DI, Neurogenic DI is caused when there is a deficiency of antidiuretic hormones in the body.

Dipsogenic DI:

Dipsogenic Diabetes Insipidus occurs when there is damage or improper functioning of the thirst mechanism in the body. It can increase thirst level to an extent that ADH secretion is suppressed with increasing the overall urine output.

Gestational DI:

Is related to pregnancy where the ADH gets destroyed by the enzyme vasopressinase produced in the placenta.