Your primary care provider or an endocrinologist (specialist of the endocrine system, which includes the pancreas) can run a variety of tests to determine if someone has diabetes.
- Fasting plasma glucose (FPG) test
- Glycated hemoglobin (A1C) test
- Random plasma glucose (RPG) test
- Oral glucose tolerance test
Diagnosis
Fasting Plasma Glucose (FPG) Test
This test involves a blood test after fasting overnight for at least eight hours. It tests a person’s blood sugar level at a specific time, with a measure of 126 mg/dL or higher indicating diabetes.
Glycated Hemoglobin (A1C) Test
Instead of only looking at blood sugar levels from a specific moment, this blood test determines a person’s average levels from the past few months. A result of:
- lower than 5.7 is normal,
- 5.7 to 6.4 indicates prediabetes, and
- 6.5 or higher is a diabetes indicator.
Random Plasma Glucose (RPG) Test
Similar to the FPG test, this blood test checks blood sugar levels at a specific moment. The difference is, it can be at any time, with fasting not required. In this case, if a person has other symptoms and has a level of 200 mg/dL or higher, it suggests diabetes.
Oral Glucose Tolerance Test
This test is for pregnant women believed to have a specific form of this condition, known as gestational diabetes (aka, diabetes during pregnancy). It involves fasting overnight and then drinking a sugary liquid in the doctor’s office the next morning. Blood sugar levels are monitored over the next two hours.
- Under 140 mg/dL is a healthy reading.
- Between 140 and 199 mg/dL indicates prediabetes.
- Over 200 mg/dL after two hours has passed indicates diabetes.
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