Which fluid or substance is primarily evaluated for diagnosing diabetes?

The evaluation of urine is a key diagnostic tool for diabetes, primarily due to the presence of glucose and ketones. When blood glucose levels rise significantly, the kidneys may not be able to reabsorb all the glucose, leading to glycosuria, which is the excretion of glucose in the urine. This is a critical indicator that prompts healthcare providers to check for diabetes.

In addition, the presence of ketones in the urine can indicate poorly controlled diabetes, particularly in individuals with type 1 diabetes, and signifies that the body is burning fat for energy instead of glucose, which is a state that can lead to ketoacidosis if untreated.

While blood serum can also be used to measure glucose levels and diagnose diabetes, the urine analysis provides unique insights into glucose handling by the kidneys and can detect issues that might not be apparent through blood testing alone. Cerebrospinal fluid and saliva do not typically provide relevant information regarding diabetes diagnosis and are less commonly used for this purpose.