If a patient exhibits symptoms of excessive thirst and hunger, which initial test can confirm a suspicion of type 2 diabetes mellitus?

The initial test that can confirm a suspicion of type 2 diabetes mellitus in a patient exhibiting symptoms such as excessive thirst and hunger is the fasting plasma glucose level. This test measures blood sugar levels after fasting for at least eight hours. A fasting plasma glucose level of 126 mg/dL or higher is diagnostic for diabetes mellitus.

The glycosylated hemoglobin level (HbA1c) is another valuable test that provides an average blood glucose level over the past two to three months. An HbA1c of 6.5% or higher indicates diabetes as well, but it is often used for monitoring and confirming the diagnosis after an initial abnormal glucose result.

Glucose tolerance testing is a more comprehensive assessment that evaluates the body's response to sugar over a specific period, but it is generally not the first-line test used for initial diagnosis.

While all the tests mentioned can assist in diagnosing diabetes, the fasting plasma glucose test is typically the first choice due to its simplicity, availability, and effectiveness in establishing a diagnosis. Therefore, the approach typically starts with this test when a patient presents symptoms consistent with diabetes.