Answer: The most likely diagnosis is Type 2 diabetes mellitus.
Explanation:
Diabetes mellitus( DM) is a metabolic disorder which occurs due to relative or chronic insulin insufficiency ( resulting from either insulin resistance or failure to produce insulin) leading to excessive sugar in the blood ( hyperglycemia). There are two major forms of diabetes mellitus: Type 1 and Type 2 DM.
Generally, polyuria( excess urination) is a common symptom seen in both types of DM. Due to excess sugar in the blood stream the kidney lowers the blood glucose by filtering out excess glucose alongside with this , water is filtered out too. This can lead to dehydration(decreased skin turgor and dry mucous membranes) if not properly handled.
In Type 1 DM, it has an early onset and in its Laboratory diagnosis, there is usually ketones in both blood and urine.
In Type 2 DM, it usually occurs in older individual.Hyperglycemic,hyperosmolar, nonketotic diabetic coma occurs only in Type 2 diabetes mellitus.