It takes more than just one abnormal blood test to diagnose diabetes.Istockphoto
For centuries, diabetes testing mostly consisted of a physician dipping his pinkie into a urine sample and tasting it to pick up on abnormally high sugar. Thankfully, testing for type 2 diabetes is lot easier now—at least for doctors.
Urine tests can still pick up diabetes. However, sugar levels need to be quite high (and diabetes more advanced) to be detected on a urine test, so this is not the test of choice for type 2 diabetes.
Almost all diabetes tests are now conducted on blood samples, which are collected in a visit to your physician or obstetrician (if you're pregnant).
More about type 2 diabetes
If you have an abnormal result—meaning blood sugar is too high—on any of these tests, you'll need to have more testing.
Many things can affect blood sugar (such as certain medications, illness, or stress).
A diabetes diagnosis requires more than just one abnormal blood sugar result.
The main types of diabetes blood tests include:
- Oral glucose-tolerance test. This test is most commonly performed during pregnancy. You typically have your blood drawn once, then drink a syrupy glucose solution and have your blood drawn at 30 to 60 minute intervals for up to three hours to see how your body is handling the glut of sugar.
Normal result: Depends on how many grams of glucose are in the solution, which can vary.
- Fasting blood sugar. This is a common test because it's easy to perform. After fasting overnight, you have your blood drawn at an early morning doctor's visit and tested to see if your blood sugar is in the normal range.
Normal result: 70-99 milligrams per deciliter (mg/dl) or less than 5.5 mmol/L
- Two-hour postprandial test. This blood test is done two hours after you have eaten ("prandial" means meal).
Normal result: 70-145 mg/dL (less than 7.9 mmol/L)
- Random blood sugar. A blood sugar test is performed regardless of when you last ate a meal.
Normal result: 70-125 mg/dL (less than 7.0 mmol/L)
- Hemoglobin A1C test. This test measures how much sugar is stuck to your red blood cells, which generally have a lifespan of three months. Therefore, this test gauges how high your blood sugar has been in recent months.
Normal result for nondiabetics: 4% to 6%.
Normal result for diabetics: 7% or lower (some groups suggest aiming for 6.5% or lower)
If a hemoglobin A1C test result is 8% or higher, it's a sign that blood sugar is not under control. However, making lifestyle changes can reduce your A1C.
Changing your lifestyle can improve test results
In the few months after her diagnosis of type 2 diabetes in early 2007, Virginia Shreve, a 51-year-old school social worker in Lynchburg, Va., wanted to follow the regimen of sensible eating and exercise that her doctor recommended. But she wasn't ready to give up her old life.
"I was compliant, but skating on the edge of compliance. I wanted to follow my diet plan, but I still wanted to eat as much as I could while keeping my blood sugar in line," she says. "Three months later I woke up and said, 'I've gotta stop fighting this thing. I'm the one being hurt in this battle.'"
She started walking three miles a day, ate healthier carbohydrates, and the results on her next hemoglobin A1C test had fallen well within the healthy range, dropping from 9.5% when she was diagnosed to 5.5% in the fall of 2007.