Diabetes is tested primarily through blood tests that measure blood sugar levels. The most common tests include:
- HbA1c (A1C) test: Measures average blood sugar levels over the past 2-3 months. An HbA1c level of 6.5% or higher on two separate tests indicates diabetes. This test does not require fasting.
- Fasting blood sugar test: Measures blood sugar after an overnight fast. Levels of 126 mg/dL (7 mmol/L) or higher on two tests indicate diabetes.
- Random blood sugar test: A blood sample taken at any time without fasting. Blood sugar of 200 mg/dL (11.1 mmol/L) or higher with symptoms suggests diabetes.
- Oral glucose tolerance test (OGTT): After fasting overnight, blood sugar is measured, then again two hours after drinking a sugary liquid. A two-hour blood sugar level of 200 mg/dL (11.1 mmol/L) or more means diabetes.
Sometimes urine tests for ketones are also used, especially to help diagnose type 1 diabetes. These tests are usually done in a healthcare setting, and a positive test often needs confirmation with a second test.
