Tests used to diagnose prediabetes and type 2 diabetes
This test measures how much glucose is attached to the hemoglobin molecule of the red blood cell. Because the red blood cell lives about 3 months, this test gives a fair assessment of how your blood glucose level has averaged over a three month period of time.
Normal: less than 5.4 mg/dl
Prediabetes: 5.5-6.4 mg/dl
Type 2 diabetes: greater than 6.5 mg/dl
This test is taken usually in the morning following an 8 hour period in which no food or caloric intake has been consumed.
Fasting blood glucose results
Normal: Less than 100 mg/dl
Prediabetes: 100-125 mg/dl
Type 2 diabetes: greater than 126 mg/dl
- OGTT: Oral glucose tolerance test
The patient is given a large glucose load and blood glucose level is measured 2 hours later. If the result is greater than 200 mg/dl, the result is indicative of type 2 diabetes.
If a finger stick performed at any time is greater than 200 mg/dl, it is diagnostic for being type-2 diabetic.
Tests used to diagnose Type 1 diabetes
Any of the above tests in addition to antibody testing. If a patient has an autoantibody associated with type 1 diabetes, this confirms the diagnosis.
This test measures how much C-peptide is in your blood. Because levels of this peptide generally match insulin levels in the body, the test can indicate how much insulin your body is producing. Low levels of C-peptide and insulin usually point to type 1 diabetes. However, low C-peptide levels can be found in patients that have had type 2 diabetes for years and have become dependent on insulin.
- Glutamic Acid Decarboxylase Autoantibodies (GADA or Anti-GAD)
This test seeks to find antibodies built against a specific enzyme in the pancreatic beta cells that produce insulin.
- Insulin Autoantibodies (IAA)
In addition to attacking beta cells, the immune system also targets insulin in people with type 1 diabetes. This test looks for the antibodies targeting insulin.
- Insulinoma-Associated-2 Autoantibodies (IA-2A)
This test looks for antibodies mounted against a specific enzyme in beta cells. Both the IA-2A and GADA tests are common type 1 antibody tests performed at endocrinology offices.