Which test is used for initial screening for type 2 diabetes according to common practice?

• A. A1c
• B. Fasting plasma glucose
• C. Oral glucose tolerance test
• D. C-peptide level

Answer: (A)

A convenient, nonfasting test that reflects longer-term glucose exposure is commonly used to screen for type 2 diabetes. The A1c fits this well because you don’t have to fast, it’s widely available, and it captures average blood glucose over about the past two to three months. This makes it practical for broad screening in primary care. In practice, an A1c of 6.5% or higher is diagnostic for diabetes (when confirmed), while 5.7% to 6.4% indicates prediabetes and signals the need for lifestyle intervention and further monitoring.

Fasting plasma glucose is also used and can diagnose diabetes, but it requires fasting and may be less convenient for routine screening. The oral glucose tolerance test is more sensitive but time-consuming and less practical for initial screening in most settings. C-peptide level measures endogenous insulin production and helps evaluate insulin deficiency or differentiate diabetes types; it’s not used for screening for diabetes.