Diagnosing diabetes type 1, type 2, or gestational diabetes as well as pre-diabetes involves a blood test to evaluate how well your body is handling glucose. Urine tests may also be used to diagnose type 1. Before diabetes is confirmed, you may have to undergo more than one blood test.
Diagnosis of type 2 diabetes
The symptoms of diabetes can be so subtle and come on so gradually that you can have diabetes for years before the symptoms become obvious enough to prompt a visit to your doctor. For that reason, it is recommended that adults over the age of 45 be tested for diabetes. In addition, if you find that you have one or more of the risk factors for diabetes, you should talk to your Riverside primary care doctor about getting tested for diabetes.
What to expect when being tested for diabetes
Depending on your individual situation, your doctor may select one of the following blood tests:
Glycated hemoglobin (A1C) test
The A1C test tells your physician your average blood sugar level for the past two to three months. Experts have recently recommended that the A1 test be used to test for type 1 and type 2 diabetes.
Here's how the A1C test works:
- If you have excess glucose in your blood, some of that glucose will hook onto the hemoglobin in your red blood cells. It stays there for the life of the red blood cell, which is about 120 days.
- The medical staff will draw a small amount of blood and send it to the lab.
- The lab will measure the percentage blood sugar attached to the hemoglobin.
- The higher your blood glucose levels, the more sugar that has been circulating in your bloodstream attaching itself to the hemoglobin.
- Because your red blood cells have a life span of about 120 days, your doctor can tell how high your glucose levels have been during the lifetime of your current red blood cells.
- Diabetes or prediabetes is diagnosed when your average levels of blood glucose fall into certain ranges.
- You'll probably have two separate tests before diabetes will be diagnosed.
Random blood sugar test
A blood sample can be taken at your doctor's office, regardless of when you last ate. A random blood sugar level of 200 milligrams per deciliter (mg/dL) — 11.1 millimoles per liter (mmol/L) — or higher suggests diabetes.
Fasting blood sugar test
For this test you'll need to be on an overnight fast. Usually, you'll be told not to eat after midnight the day before a blood sample is to be taken. A fasting blood sugar level between 70 and 99 mg/dL (3.9 and 5.5 mmol/L) is normal. If it's 126 mg/dL (7 mmol/L) or higher, you will be asked to take a another fasting test. If your blood sugar levels are above 126 on two separate tests, you'll be diagnosed with diabetes.
Blood glucose tolerance test
The glucose tolerance test is done in several steps. You'll be instructed not to have anything to eat for eight hours before the test. You may want to schedule you test first thing in the morning, so you can fast overnight.
- When you arrive at your doctor's office or lab, a member of your health care team will take a sample of blood by pricking your fingertip or inserting a needle into a vein in your arm. This blood sample will be used to measure your blood sugar level after the eight hour fast.
- You'll drink about 8 ounces of a syrupy glucose solution that contains sugar. The glucose solution is often cola or orange-flavored. Two hours later, your blood sugar level will be measured again. If you are being tested for gestational diabetes, your blood sugar level will be tested one, two and three hours later.
- After drinking the glucose solution, you'll likely need to remain in the doctor's office or lab while you're waiting for your blood sugar level to be tested. After the glucose tolerance test, you can return to your usual activities immediately. Your doctor will follow up with you on the results of your test.
- Understanding the results of your diabetes test
- Blood sugar monitoring: Why, where and how