A glucose tolerance test measures how well your body’s cells are able to absorb glucose (sugar) after you consume a specific amount of sugar.
Doctors use fasting blood sugar levels and hemoglobin A1c values to diagnose type 1 and type 2 diabetes as well as prediabetes.
Doctors primarily use a glucose tolerance test to diagnose diabetes during pregnancy (called gestational diabetes).
Doctors often diagnose type 1 diabetes quickly because it usually develops rapidly and involves high blood sugar levels and symptoms.
Type 2 diabetes, on the other hand, often develops over years. Type 2 diabetes is the most common form of diabetes, and it usually develops during adulthood.