Prediabetes: the numbers, the risk test and what comes next

What prediabetes is

CDC describes prediabetes as blood sugar levels that are higher than normal but not high enough for a type 2 diabetes diagnosis (CDC). It is not a disease with its own symptoms. It is a range on a lab test, and it matters because people in that range are more likely to go on to develop type 2 diabetes.

It is also very common. CDC estimates that 115.2 million US adults had prediabetes in 2023 (CDC), which is more than 2 in 5 adults (CDC). Most people in that group feel completely well.

Prediabetes ranges by test

Three blood tests are used. Any one of them can show prediabetes. The cutoffs below are the ones in the American Diabetes Association's Standards of Care (ADA Standards 2026), and CDC uses the same A1C ranges (CDC).

To see what an A1C means in meter units, use the A1C to average glucose calculator.

Doctors sometimes use the older names for the glucose results: impaired fasting glucose for a fasting value of 100 to 125 mg/dL, and impaired glucose tolerance for a 2-hour value of 140 to 199 mg/dL (ADA Standards 2026). A diagnosis of diabetes normally needs two abnormal results, either from the same blood sample or from two separate samples, unless the picture is already clear (ADA Standards 2026).

When an A1C result can mislead

The A1C test measures how much sugar is attached to red blood cells, so anything that changes red blood cells can push the number up or down. CDC lists severe anemia, kidney failure, liver disease, blood disorders such as sickle cell anemia or thalassemia, some medicines (including opioids and some HIV drugs), blood loss or a transfusion, and early or late pregnancy (CDC). If one of these applies to you, tell the person ordering the test. A glucose test may be a better choice.

How a prediabetes risk test works

A risk test is not a blood test. It is a short questionnaire that gives points for things that raise the chance of high blood sugar, so you can decide whether a blood test is worth asking for. CDC hosts a Prediabetes Risk Test (CDC), and the ADA hosts a Type 2 Diabetes Risk Test (ADA).

The ADA test, which is the one our diabetes risk test follows, asks about age, sex, gestational diabetes, a parent or sibling with diabetes, high blood pressure, physical activity and weight for height (ADA). The score behind it was built to flag adults with undiagnosed type 2 diabetes, and a score of 5 or more was the point at which a blood test was suggested (Bang 2009). It was not designed to detect prediabetes on its own, but the same risk factors drive both, so a high score is a good reason to ask about an A1C or fasting glucose. The full scoring is on our explainer for the diabetes risk test.

A questionnaire can miss things. CDC also lists race and ethnicity, non-alcoholic fatty liver disease and having had a baby who weighed over 9 pounds as risk factors (CDC). A low score does not rule anything out. It only means the questions found fewer risk factors.

Who should get a blood test

You do not need a high score to be tested. The US Preventive Services Task Force recommends screening for prediabetes and type 2 diabetes in adults aged 35 to 70 who have overweight or obesity (USPSTF 2021). The ADA goes further and recommends testing all adults starting at age 35, and testing earlier for adults with overweight or obesity who have at least one other risk factor (ADA Standards 2026). For Asian American adults, the ADA uses a lower BMI line of 23 when deciding whether to test (ADA Standards 2026).

If a result comes back in the prediabetes range, the ADA recommends repeating the test at least once a year (ADA Standards 2026). The diabetes screening age check shows which of these rules fits you.

What the research says about lowering the risk

The best-known study is the Diabetes Prevention Program, a US trial of 3,234 adults with raised blood sugar who did not yet have diabetes (DPP 2002). One group followed a structured lifestyle program with goals of losing at least 7% of body weight and getting at least 150 minutes of physical activity a week. Over an average of 2.8 years, that group developed diabetes 58% less often than the placebo group. A group given the drug metformin developed it 31% less often (DPP 2002).

CDC's National Diabetes Prevention Program is built on that research. CDC says it can lower the risk of type 2 diabetes by 58%, or 71% for people over 60, and it describes a weight loss goal of about 5% to 7% of body weight, around 10 to 14 pounds for a 200-pound person, together with 150 minutes of activity a week (CDC). The USPSTF recommends that clinicians offer or refer people with prediabetes to effective preventive programs like these (USPSTF 2021).

These are results for groups of people in a trial and in a program, not a promise for any one person. Whether a program, a medicine or simply a repeat test is right for you is a decision to make with your own clinician.

Common questions

Is an A1C of 5.7 prediabetes?

Yes. On the ADA and CDC ranges, an A1C from 5.7% to 6.4% is in the prediabetes range, and 6.5% or higher is in the diabetes range (ADA Standards 2026) (CDC). One result is a starting point. Your clinician may repeat it or check a glucose test as well.

Is a fasting blood sugar of 100 prediabetes?

A fasting plasma glucose of 100 to 125 mg/dL is in the prediabetes range (ADA Standards 2026). Home finger-stick meters are not used for diagnosis. The cutoffs apply to a lab test.

Does prediabetes have symptoms?

Usually not. That is why testing is based on age and risk factors rather than on how you feel (USPSTF 2021).

Can an online prediabetes risk test tell me if I have prediabetes?

No. It can tell you whether your answers match the risk factors that make a blood test worthwhile. Only an A1C, fasting glucose or glucose tolerance test can show whether your blood sugar is in the prediabetes range.

Does everyone with prediabetes get type 2 diabetes?

No. In the Diabetes Prevention Program, many people in every group, including the placebo group, had not developed diabetes by the end of the study (DPP 2002). Prediabetes raises the risk. It does not decide the outcome.

Take the diabetes risk test or see which numbers to ask your doctor for.