Getting tested for diabetes is straightforward: you can ask your primary care doctor for a blood test, visit a walk-in lab, or start with an at-home screening kit. Most people will get one of three standard blood tests, all of which can detect both prediabetes and type 2 diabetes. If you’re 35 or older, or younger with certain risk factors, screening is recommended even if you feel perfectly fine.
Who Should Get Tested
The American Diabetes Association recommends that all adults 35 and older be screened for prediabetes and type 2 diabetes, regardless of risk factors. Before 2022, that threshold was 45, so if you heard the older guideline, it’s worth knowing the bar is now lower.
If you’re under 35, screening is still recommended if you’re overweight or obese and have at least one additional risk factor. Those risk factors include:
- Race or ethnicity: African American, Hispanic or Latino, American Indian, Alaska Native, Pacific Islander, or Asian American individuals face higher risk.
- Family history: A parent or sibling with type 2 diabetes.
- History of gestational diabetes: Diabetes during a previous pregnancy.
- Polycystic ovary syndrome (PCOS).
- Physical inactivity.
- History of cardiovascular disease.
You don’t need symptoms to get tested. In fact, prediabetes rarely causes noticeable symptoms, and many people with type 2 diabetes go years before they’re diagnosed. Screening catches the problem early, often while it’s still reversible.
The Three Main Tests
Doctors use three blood tests to screen for and diagnose diabetes. Any of them can be ordered as a first step, and each measures your blood sugar in a slightly different way.
A1C Test
This is the most convenient option. The A1C test measures your average blood sugar over the past two to three months by looking at how much sugar has attached to your red blood cells. No fasting required. A normal result is below 5.7%. A result between 5.7% and 6.4% indicates prediabetes, and 6.5% or higher indicates diabetes.
Fasting Plasma Glucose Test
This test measures your blood sugar after you’ve fasted for 8 to 12 hours, so it’s typically done first thing in the morning. You can drink plain water during the fast but nothing else. A normal fasting level is below 100 mg/dL. Between 100 and 125 mg/dL signals prediabetes, and 126 mg/dL or higher points to diabetes.
Oral Glucose Tolerance Test
This one takes more time. You fast overnight, give a blood sample, then drink a sugary solution containing 75 grams of glucose. Your blood is drawn again at intervals over the next two to three hours to see how your body handles the sugar load. A two-hour reading below 140 mg/dL is normal. Between 140 and 199 mg/dL indicates prediabetes, and 200 mg/dL or above indicates diabetes. This test is more involved, so it’s used less often for routine screening but is standard during pregnancy.
If You Already Have Symptoms
Classic diabetes symptoms include frequent urination, excessive thirst, and unexplained weight loss. If you’re experiencing these, your doctor can run a random plasma glucose test, which is a blood draw taken at any time of day without fasting. A result of 200 mg/dL or higher, combined with those symptoms, is enough to diagnose diabetes on the spot, without a second confirmatory test.
This is the one scenario where a single test result is considered definitive. For every other situation, diagnosis requires confirmation.
How a Diagnosis Gets Confirmed
One abnormal screening result doesn’t automatically mean you have diabetes. Unless you have clear symptoms with a random glucose of 200 mg/dL or above, the ADA’s 2025 guidelines require two abnormal results to confirm a diagnosis. This can happen in two ways: two abnormal results from different tests drawn at the same visit (for example, an A1C and a fasting glucose both above their thresholds), or a repeat of the same test at a separate appointment.
If two different tests give conflicting results, the one that came back abnormal should be repeated. And if your numbers land right near the borderline, your doctor will likely retest in three to six months rather than making an immediate call.
Where to Get Tested
The simplest route is to ask your primary care doctor at your next visit or schedule an appointment specifically for diabetes screening. The test itself is a basic blood draw or finger prick, and results usually come back within a day or two. Many urgent care clinics and walk-in labs also offer these tests without a referral.
Under the Affordable Care Act, diabetes screening is classified as a preventive service. Private insurance plans are required to cover it with no copay or deductible for eligible populations. If you’re uninsured, community health centers and local health departments often provide low-cost screening.
At-Home A1C Kits
Over-the-counter A1C test kits let you check your levels at home using a finger prick. In a clinical evaluation, about 93% of at-home A1C results fell within an acceptable accuracy range compared to lab values, and the correlation with lab results was strong. They’re a reasonable first step if you want a general sense of where you stand before making a doctor’s appointment.
That said, an at-home kit can’t replace a clinical diagnosis. If your result comes back in the prediabetes or diabetes range, you’ll still need a lab-confirmed test to make it official and start any treatment plan. Think of at-home kits as a screening tool, not a final answer.
Testing During Pregnancy
Gestational diabetes screening follows its own timeline. The U.S. Preventive Services Task Force recommends testing between 24 and 28 weeks of pregnancy for people without prior diabetes symptoms. Most practices use a two-step approach: first a one-hour glucose challenge test (you drink a sugary solution and get one blood draw an hour later), and if that result is elevated, a longer oral glucose tolerance test to confirm.
Some providers use a one-step approach, going straight to the full oral glucose tolerance test. Either way, gestational diabetes screening is a routine part of prenatal care, and your OB provider will schedule it for you.
What to Do With Your Results
If your results come back normal, the general recommendation is to retest every three years, or sooner if your risk factors change, such as significant weight gain or a new diagnosis like PCOS.
A prediabetes result (A1C of 5.7% to 6.4%, fasting glucose of 100 to 125 mg/dL, or a two-hour glucose tolerance reading of 140 to 199 mg/dL) means your blood sugar is elevated but not yet in the diabetes range. This is the stage where lifestyle changes like losing 5% to 7% of your body weight and getting regular physical activity can meaningfully reduce your risk of progressing to type 2 diabetes. Your doctor will likely recommend retesting annually.
If your results confirm diabetes, you’ll typically be referred to a diabetes care team to discuss management options, which vary depending on the type and severity. The earlier diabetes is caught, the more options you have for keeping it under control and preventing complications.