These Are the Most Common Blood Tests To Diagnose Diabetes

Constant thirst, excessive urination, or sudden weight gain or loss are classic symptoms of diabetes. But many people with diabetes, especially gestational diabetes or type 2 diabetes, don't have symptoms or only have subtle signs during the early stages of the illness, as described in a 2015 review in Medical Clinics of North America.

Several types of blood tests often show abnormal blood sugar levels before the condition progresses and serious complications start to occur. Here's what you need to know about them.

Diabetes Testing

Anyone who has symptoms of diabetes or risk factors for diabetes should be tested, per the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Testing allows health care professionals to diagnose diabetes sooner and start to put into place a management plan to prevent complications.

Blood Tests for Diabetes

According to the Centers for Disease Control and Prevention (CDC), you'll need to get your blood sugar tested to find out for sure if you have prediabetes or type 1, type 2, or gestational diabetes. The good news is that testing is simple, and results are usually available quickly.

There are several tests to diagnose diabetes. Sometimes tests need to be repeated on a different day to verify a diagnosis of diabetes. However, according to the American Diabetes Association (ADA), if a healthcare professional determines that your blood glucose level is very high, or if you have classic symptoms of high blood glucose in addition to one positive test, they may not require a second test to diagnose diabetes.

The main types of diabetes blood tests include the following.

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 excess sugar.

Normal result: This depends on how many grams of glucose are in the solution, which can vary. According to the ADA, diabetes is diagnosed at a two-hour blood glucose of greater than or equal to 200 mg/dl.

Fasting Blood Sugar

This is a common test. After fasting overnight, you have your blood drawn in the morning and tested to see if your blood sugar is in the normal range.

Normal result: A result of 70-99 milligrams per deciliter (mg/dl) or less than 5.5 mmol/L is considered standard. According to the ADA, diabetes is diagnosed at fasting blood glucose of greater than or equal to 126 mg/dl.

Random Blood Sugar

A blood sugar test is performed regardless of when you last ate a meal.

Normal result: A blood glucose result of 199 mg/dl or less is considered normal for this test. According to the ADA, diabetes is diagnosed at blood glucose of greater than or equal to 200 mg/dl.

Hemoglobin A1C Test

According to ADA, the A1C test measures your average blood glucose for the past two to three months. The advantage of this test is that you don't have to fast or drink anything.

This test measures how much sugar is attached to your red blood cells, which generally have a lifespan of three months. The results gauge how high your blood sugar has been in recent months.

Normal result: A result of A1C of less than 5.7% is considered a normal result. Diabetes is diagnosed at an A1C of greater than or equal to 6.5%.

Urine Tests for Diabetes

Urine tests can detect high sugar levels, and the results may help diagnose diabetes. Sugar levels need to be quite high (and diabetes more advanced) to be detected on a urine test, so this is not the most sensitive test for diabetes.

Urine testing is fast, doesn't require any blood drawn, and you can often get the results within minutes in the healthcare professional's office during your visit. These tests are often used as a quick screening tool or to follow how well your diabetes is controlled if you've already been diagnosed.

Diabetes Treatment Plan

According to the CDC, if your test results show you have type 1, type 2, or gestational diabetes, you should speak with a healthcare professional about a detailed treatment plan and specific steps you can take to be your healthiest and avoid diabetes complications.

The CDC says that the right education, support, and resources can help you improve your quality of life with diabetes. It's important to learn how to manage diabetes by eating well, engaging in physical activity, managing diabetes during sick days, reaching and maintaining a healthy weight, and managing stress and mental health.

A Personal Story

Following a diabetes treatment plan can be challenging, but it can prevent complications. Blood tests that are used to diagnose diabetes can get you on track before it's too late. One woman who shared her story explained her hesitancy to make adjustments to her daily life, but she eventually found that her efforts led to real changes.

In the few months after being diagnosed with type 2 diabetes in early 2007, Virginia Shreve, a 51-year-old school social worker in Lynchburg, Va., initially 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," said Shreve. "Three months later I woke up and said, 'I've gotta stop fighting this thing. I'm the one being hurt in this battle.'"

Shreve 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.

A Quick Review

Blood tests are an important tool to diagnose diabetes. You can expect to have screening tests if you go for your recommended routine medical checkups. Screening tests are also commonly ordered during an assessment by a healthcare professional for symptoms that could be related to diabetes. If your tests or symptoms suggest diabetes, you can expect to have more specific, confirmatory tests as you and your healthcare provider create a plan of action.

And if you are diagnosed with diabetes, these tests are also valuable for you and your healthcare providers as you assess how well your treatment is working, and whether you need any adjustments to your diabetes management plan.