What diseases cause deficiency of water in body?

Several diseases can lead to water deficiency in the body, primarily through excessive fluid loss. Conditions such as Diabetes insipidus, where the body fails to concentrate urine, can result in significant dehydration. Gastroenteritis, characterized by vomiting and diarrhea, also contributes to rapid fluid loss. Additionally, uncontrolled diabetes mellitus may lead to dehydration due to high blood sugar levels causing increased urination.