Prediabetes can be easy to overlook.
You may feel perfectly healthy, go about your normal routine and have no obvious reason to think your blood sugar is higher than it should be.
Yet prediabetes means blood glucose levels are above the normal range but have not reached the threshold used to diagnose diabetes.
The important part is the word “pre.”
Finding abnormal blood sugar before type 2 diabetes develops can give you and your healthcare provider an opportunity to address risk factors and decide what should happen next.
So how would you know if you have prediabetes?
Often, the answer begins with a blood test.
What Is Prediabetes?
Prediabetes occurs when your body isn't regulating blood glucose as effectively as it should.
When you eat carbohydrates, your digestive system breaks many of them down into glucose. Glucose enters your bloodstream, and your pancreas releases insulin.
Insulin helps glucose move from the bloodstream into cells where it can be used for energy.
Over time, some people's cells become less responsive to insulin. This is known as insulin resistance.
The pancreas may initially compensate by producing more insulin. Eventually, however, blood glucose can begin to rise.
Prediabetes can be an early warning that this process is occurring.
→ Compare Diabetes Blood Tests
Can You Have Prediabetes Without Knowing It?
Yes.
One of the problems with prediabetes is that it frequently doesn't produce obvious symptoms.
Someone can therefore have abnormal blood glucose while feeling completely well.
That's why testing can be particularly important for people with relevant risk factors.
These can include factors such as:
- Being overweight or obese
- Physical inactivity
- Family history of type 2 diabetes
- Increasing age
- Previous gestational diabetes
- Polycystic ovary syndrome (PCOS)
- High blood pressure
- Abnormal cholesterol or triglycerides
Having one or more risk factors does not mean you have prediabetes. It means screening may be worth discussing with a healthcare professional.
What Are the Possible Warning Signs?
Prediabetes itself often causes no noticeable symptoms.
If blood glucose becomes substantially elevated, symptoms associated with diabetes can include:
- Increased thirst
- Frequent urination
- Increased hunger
- Unexplained weight loss
- Fatigue
- Blurred vision
- Slow-healing wounds
These symptoms can have many causes, so symptoms alone cannot diagnose diabetes.
If persistent tiredness is what led you to investigate your health, you may also want to read Feeling Tired All the Time? 7 Blood Tests That May Help You Find Out Why.
1. Hemoglobin A1c: One of the Most Useful Blood Sugar Tests
The Hemoglobin A1c test, usually called HbA1c or simply A1c, is one of the most familiar tests used when assessing blood sugar.
Unlike a single glucose reading, A1c provides information about your average blood glucose over roughly the previous two to three months.
That makes it useful because your result isn't simply a snapshot of what your blood sugar happened to be at one particular moment.
For many people, an A1c test also doesn't require fasting.
USLabTesting currently lists an individual Hemoglobin A1c test within its diabetes-testing section.
→ View the Hemoglobin A1c Test
What A1c Level Indicates Prediabetes?
A1c results are generally reported as a percentage.
Commonly used diagnostic ranges are:
- Below 5.7%: generally considered normal
- 5.7% to 6.4%: prediabetes range
- 6.5% or higher: diabetes range
However, diagnosis should not be made from an online article or interpreted in isolation.
Certain medical conditions can also affect A1c accuracy, and an abnormal result may need to be confirmed or evaluated with additional testing.
Discuss abnormal results with a qualified healthcare professional.
2. Fasting Blood Glucose
Another common way to investigate blood sugar is a fasting glucose test.
As the name suggests, this measures the amount of glucose in your bloodstream after a period without eating.
Because food can temporarily raise blood glucose, fasting provides a more standardized measurement.
A fasting glucose result can help identify abnormal glucose regulation, but—as with A1c—the result needs to be interpreted appropriately.
→ Explore Diabetes Testing Options
3. Fasting Insulin
Blood glucose isn't the only measurement that may be relevant.
A fasting insulin test measures the amount of insulin circulating in your blood after fasting.
Why might that be interesting?
During insulin resistance, the body may need to produce increasing amounts of insulin to keep blood glucose under control.
That means insulin levels and glucose levels provide different pieces of information.
Fasting insulin is not a stand-alone diagnostic test for prediabetes, however, and interpretation can be more complicated than simply deciding whether a number is “high” or “low.”
USLabTesting currently lists a dedicated fasting insulin test.
→ View the Fasting Insulin Test
4. A Diabetes Panel
Sometimes it makes more sense to look at several related measurements rather than ordering one test in isolation.
USLabTesting lists a Diabetes Panel designed to assess blood sugar and insulin-related measurements together.
A panel can provide a broader picture than a single measurement, depending on exactly what is included.
Always check the individual biomarkers included in a panel before ordering because similarly named panels can differ between providers.
What Does Cholesterol Have to Do With Prediabetes?
Blood glucose doesn't exist in isolation from the rest of your metabolic health.
People with insulin resistance or type 2 diabetes may also have abnormalities involving triglycerides, HDL cholesterol and other cardiovascular risk factors.
That's one reason broader health assessments often look at blood sugar and cholesterol together.
If you're interested in understanding cholesterol better, continue with Top 10 Tips to Manage High Cholesterol.
→ Explore Cardiac Health and Cholesterol Tests
Can Prediabetes Be Reversed?
Prediabetes does not mean that progression to type 2 diabetes is inevitable.
For some people, changes involving weight, diet and physical activity can significantly improve blood glucose regulation.
The appropriate approach depends on the individual.
Common areas a healthcare professional may discuss include:
- Increasing physical activity
- Losing excess weight where appropriate
- Eating more fiber-rich whole foods
- Reducing highly refined carbohydrates and added sugars
- Improving overall diet quality
- Getting adequate sleep
- Managing blood pressure and cholesterol
- Stopping smoking
- Monitoring blood glucose over time
Some people may also require medication based on their individual circumstances and risk.
If you're looking for ideas around healthier dietary patterns, USLabTesting already has a guide to The World's Healthiest Cuisines: How Global Diets Help Prevent Chronic Illness.
Prediabetes and Heart Health
The reason to pay attention to abnormal blood sugar isn't limited to whether someone eventually develops diabetes.
Metabolic risk factors frequently overlap.
Blood glucose, blood pressure, cholesterol, body weight, smoking and physical activity can all form part of a person's overall cardiovascular risk profile.
If you're working on your metabolic health, it therefore makes sense to think beyond a single glucose number.
You can read more in What You Need to Know About Heart Attacks: Prevention, Symptoms, and Gender Differences.
What About Your Kidneys?
Diabetes can affect the kidneys over time, which is another reason early identification and appropriate management of abnormal blood sugar matters.
Kidney function can be assessed using measurements such as creatinine and estimated glomerular filtration rate (eGFR), while urine testing can provide additional information.
For more information, read Signs of Kidney Disease: Recognizing the Early Warning Signs.
You can also read Understanding Creatinine: What It Is and Its Importance.
→ Explore Kidney and Liver Tests
Should You Test for Prediabetes Even If You Feel Healthy?
Possibly, depending on your age and risk factors.
The important thing to understand is that feeling healthy doesn't necessarily tell you what your blood glucose is doing.
That's what makes conditions such as prediabetes different from illnesses that immediately produce obvious symptoms.
Screening recommendations aren't identical for everyone, so a healthcare professional can help determine whether testing is appropriate and how frequently it should be repeated.
Which Test Should You Choose?
If your main question is simply whether your average blood glucose has been elevated, A1c is one commonly used option.
→ View the Hemoglobin A1c Test
If you're interested in insulin specifically:
→ View the Fasting Insulin Test
If you want to compare broader testing options:
Or browse everything available in this category:
→ Compare Diabetes Blood Tests
The Bottom Line
Prediabetes can be easy to miss because you may have no obvious symptoms.
Blood tests such as Hemoglobin A1c and fasting glucose can provide information about how your body is regulating blood sugar, while additional measurements may sometimes provide useful context.
An abnormal result doesn't mean you should panic, and one number shouldn't be viewed in isolation.
Instead, use your results as information to discuss with a healthcare professional, who can consider them alongside your medical history, medications, symptoms and individual risk factors.
Finding abnormal blood sugar earlier may provide an opportunity to make changes before more serious problems develop.
→ Compare Diabetes Testing Options on USLabTesting
Important Medical Disclaimer
This article is provided for general informational and educational purposes only and is not intended to provide medical advice, diagnosis or treatment. Prediabetes and diabetes should be diagnosed and managed by an appropriately qualified healthcare professional. Laboratory reference ranges and interpretation can vary, and abnormal results may require confirmation or additional testing. If you have symptoms or concerns about your blood sugar, discuss them with a healthcare professional.