The doctor will ask about your symptoms and health history. An exam will be done. These blood tests may be done:
Random Plasma Glucose Test
This test is taken at a random time. It does not matter when food was last eaten. A blood sample will be taken. The glucose level will be measured. A measure of 200 (mg/dl) [11.1 mmol/L] or higher is a sign of diabetes.
Two-hour Glucose Tolerance Test
This test is done after a person has not eaten for 8 to 16 hours. It is often done in the morning.
A blood sample will be taken to measure glucose levels. Then, a drink that has 75 grams of glucose will be given. Two hours later, another blood sample will be taken. In a person with diabetes, the glucose level will rise higher than normal and stay high for a much longer time. A measure of 200 mg/dl (7 mmol/L) or above at 2 hours is a sign of diabetes.
Hemoglobin A1c (HbA1c)
The HbA1c test measures blood glucose levels over the past 2 to 4 months. A fast is not needed before the test. A blood sample will be taken. An HBA1c level of 6.5% or higher is a sign of diabetes.
Fasting Plasma Glucose Test
This test is done after a person has not eaten for at least 8 hours. A sample of blood will be taken to measure glucose levels. A measure of 126 milligrams per deciliter (mg/dl) (7 millimole per liter of blood [mmol/L]) or higher is a sign of diabetes.
References
American Diabetes Association. Standards of medical care in diabetes—2019. Diabetes Care, 2019; 42 (Suppl 1): S1-193.
Diabetes mellitus type 1. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/diabetes-mellitus-type-1-39. Accessed May 5, 2022.
Type 1 diabetes. American Diabetes Association website. Available at: https://www.diabetes.org/diabetes/type-1. Accessed May 5, 2022.
Revision Information
- Reviewer: EBSCO Medical Review Board James P. Cornell, MD
- Review Date: 03/2022
- Update Date: 05/05/2022