Prediabetes means your blood sugar is higher than normal but not yet high enough to be diagnosed as type 2 diabetes.
It is sometimes informally called borderline diabetes, but prediabetes is the medical term.
Being diagnosed with prediabetes does not mean you will inevitably develop type 2 diabetes. It does mean your risk is higher, and it gives you an important opportunity to take action.
Many people with prediabetes feel completely normal. That is one reason blood testing is so important. You can have elevated blood sugar for years without realizing it.
The encouraging part is that changes in eating habits, physical activity, weight when appropriate, sleep, and other aspects of your health can improve blood sugar and significantly reduce the risk of progressing to type 2 diabetes. Some people at particularly high risk may also benefit from medication.
Quick Answer: What Is Prediabetes?
Prediabetes is a condition in which blood glucose levels are above the normal range but below the level used to diagnose diabetes.
Prediabetes is commonly associated with insulin resistance, which means cells in your muscles, fat, and liver do not respond to insulin as effectively as they should.
The three commonly used blood tests for identifying prediabetes are:
| Test | Prediabetes Range |
|---|---|
| A1C | 5.7% to 6.4% |
| Fasting plasma glucose | 100 to 125 mg/dL |
| 2-hour oral glucose tolerance test | 140 to 199 mg/dL |
Prediabetes usually causes no obvious symptoms, so testing is the only reliable way to know whether you have it.
Key Takeaways
- Prediabetes means blood sugar is higher than normal but not yet in the diabetes range.
- Prediabetes commonly develops along with insulin resistance.
- Most people with prediabetes do not have noticeable symptoms.
- An A1C of 5.7% to 6.4%, fasting glucose of 100 to 125 mg/dL, or 2-hour glucose of 140 to 199 mg/dL on an oral glucose tolerance test falls within the prediabetes range.
- Prediabetes increases your risk of developing type 2 diabetes, but progression is not inevitable.
- Healthy eating, regular physical activity, weight management when appropriate, and other lifestyle changes can substantially reduce the risk of type 2 diabetes.
- Some people at particularly high risk may benefit from medication such as metformin.
- If you have prediabetes, regular follow-up testing is important even if you feel well.
What Happens When You Have Prediabetes?
Your body uses glucose as an important source of energy.
After you eat carbohydrates, your digestive system breaks them down into glucose, which enters your bloodstream. Your pancreas responds by releasing insulin.
Insulin acts like a signal that helps glucose move from your bloodstream into cells, where it can be used for energy.
In many people who develop prediabetes, cells become less responsive to insulin. This is called insulin resistance.
At first, your pancreas may compensate by producing more insulin. But over time, it may become increasingly difficult for your body to keep blood glucose within the normal range.
Blood sugar begins to rise.
When glucose levels are above normal but have not reached the threshold for diabetes, you have prediabetes.
If you want to learn more about the condition that often underlies prediabetes, our guide to an insulin resistance diet explains insulin resistance and the role food choices can play in managing it.
What Blood Sugar Levels Mean You Have Prediabetes?
Prediabetes is diagnosed with blood tests rather than symptoms.
Three tests are commonly used: the A1C test, fasting plasma glucose test, and oral glucose tolerance test.
A1C Test
The A1C test estimates your average blood glucose over approximately the previous two to three months.
In general:
- Below 5.7%: Normal range
- 5.7% to 6.4%: Prediabetes range
- 6.5% or higher: Diabetes range
A major advantage of A1C testing is that you usually do not have to fast before the test.
However, A1C is not equally reliable in every situation. Certain forms of anemia, hemoglobin variants, pregnancy, kidney disease, recent blood loss or transfusion, and other conditions can affect the result.
Your healthcare provider can determine whether A1C is an appropriate test for you.
Fasting Plasma Glucose Test
A fasting plasma glucose test measures your blood glucose after you have gone without food for at least eight hours.
Results are generally interpreted as:
- 99 mg/dL or below: Normal range
- 100 to 125 mg/dL: Prediabetes range
- 126 mg/dL or higher: Diabetes range
Unlike A1C, this test provides a measurement of your glucose at a particular point in time.
Oral Glucose Tolerance Test
An oral glucose tolerance test (OGTT) measures how your body handles a specific amount of glucose.
After fasting, you drink a glucose solution and your blood glucose is measured. For diagnosing prediabetes in nonpregnant adults, the two-hour result is generally interpreted as:
- 139 mg/dL or below: Normal range
- 140 to 199 mg/dL: Prediabetes range
- 200 mg/dL or higher: Diabetes range
The OGTT takes longer and is less convenient than A1C or fasting glucose testing, so it is not used as routinely.
Different tests can sometimes produce different results because they measure different aspects of glucose metabolism. Your healthcare provider may repeat a test or use another test when results are unclear.
For a broader explanation of glucose numbers, see our Blood Sugar Chart.
What Causes Prediabetes?
There is no single cause of prediabetes.
For many people, it develops through a combination of insulin resistance, genetics, body composition, physical activity, age, and other metabolic and health factors.
Researchers do not completely understand why some people develop insulin resistance while others do not.
What we do know is that certain factors make prediabetes and type 2 diabetes more likely.
Excess Weight and Abdominal Fat
Having overweight or obesity can increase the risk of insulin resistance and prediabetes, particularly when excess fat is concentrated around the abdomen.
But body weight is not the entire story.
People at many different body sizes can develop prediabetes, which is why weight alone should never be used to determine whether someone does or does not need testing.
Physical Inactivity
Your muscles use glucose for energy, and physical activity can improve the body’s sensitivity to insulin.
Being physically inactive is associated with a greater risk of developing insulin resistance and prediabetes.
Genetics and Family History
Having a parent or sibling with type 2 diabetes increases your risk.
Genetics can influence how your body produces insulin, responds to insulin, stores fat, and regulates glucose.
Family history does not mean diabetes is inevitable. It simply means your underlying risk may be higher.
Age
The risk of prediabetes and type 2 diabetes increases with age, although younger adults, teenagers, and children can also develop these conditions.
Current diabetes screening recommendations reflect this increased risk with age.
History of Gestational Diabetes
If you developed gestational diabetes during pregnancy, your future risk of prediabetes and type 2 diabetes is higher.
Regular follow-up glucose testing remains important even after blood sugar returns to normal following pregnancy.
Other Health Conditions
Prediabetes and insulin resistance are also associated with conditions such as:
- Polycystic ovary syndrome (PCOS)
- High blood pressure
- Unhealthy cholesterol or triglyceride levels
- Metabolic syndrome
- Metabolic dysfunction-associated steatotic liver disease (MASLD)
- Sleep apnea
Some medications can also increase blood glucose or the risk of developing diabetes.
Who Should Be Tested for Prediabetes?
You do not need to have symptoms to benefit from screening.
Current recommendations call for screening adults beginning at age 35, even when they do not have other known risk factors.
Testing may be appropriate earlier if you have overweight or obesity plus one or more additional risk factors, such as:
- A parent or sibling with diabetes
- Physical inactivity
- High blood pressure
- Unhealthy cholesterol or triglyceride levels
- Polycystic ovary syndrome
- A history of cardiovascular disease
- A condition associated with insulin resistance
- A history of gestational diabetes
- Belonging to a population with a higher risk of type 2 diabetes
Children and adolescents with overweight or obesity may also need screening when additional diabetes risk factors are present.
If your test results are normal, screening is generally repeated at least every three years, although your healthcare provider may recommend testing sooner depending on your health and risk factors.
If you already have prediabetes, testing for type 2 diabetes is generally recommended every year.
Does Prediabetes Cause Symptoms?
Usually, prediabetes has no noticeable symptoms.
You may feel perfectly healthy even though your glucose is above the normal range.
Some people with insulin resistance develop acanthosis nigricans, which causes areas of darker, thicker, velvety skin, commonly around the neck, armpits or groin.
Symptoms such as increased thirst, frequent urination, unexplained weight loss, fatigue and blurred vision can occur when blood glucose becomes more elevated. These symptoms deserve medical evaluation because they may indicate that glucose has progressed further into the diabetes range or may have another cause.
Do not wait for symptoms before getting tested if you have risk factors.
For a more detailed discussion, see Prediabetes Symptoms.
Is Prediabetes the Same as Borderline Diabetes?
The term borderline diabetes is commonly used to describe prediabetes, but it can give the wrong impression.
Prediabetes is not simply a situation where you are “almost diabetic.”
It is a recognized metabolic condition associated with increased risk of type 2 diabetes and cardiovascular disease.
At the same time, having prediabetes does not mean that progression to diabetes is unavoidable.
Think of a prediabetes diagnosis as information about your current metabolic health and future risk. It gives you and your healthcare provider an opportunity to intervene before glucose rises further.
Does Prediabetes Always Turn Into Type 2 Diabetes?
No.
Prediabetes increases your risk of developing type 2 diabetes, but not everyone with prediabetes progresses to diabetes.
Some people remain in the prediabetes range for years. Others return to glucose levels below the prediabetes range, particularly after making effective lifestyle changes. Others eventually develop type 2 diabetes.
Your individual risk depends on many factors, including how elevated your glucose is, your age, family history, body composition, physical activity, and other health conditions.
Prediabetes should therefore be taken seriously without treating a future diabetes diagnosis as inevitable.
Can Prediabetes Be Reversed?
You will often hear that prediabetes can be “reversed.”
There is some truth to that statement, but it deserves explanation.
Many people can improve their insulin sensitivity and lower their glucose enough that their test results no longer fall within the prediabetes range.
That is an excellent outcome.
However, returning to a normal glucose range does not necessarily mean that your underlying susceptibility to type 2 diabetes has permanently disappeared.
For that reason, it may be more useful to think in terms of improving prediabetes and reducing your future diabetes risk rather than assuming the condition has been permanently cured.
The lifestyle habits that helped improve your blood sugar generally need to continue.
Why Prediabetes Matters Even Before Diabetes Develops
The primary concern with prediabetes is the increased risk of progressing to type 2 diabetes.
But that is not the only concern.
Prediabetes frequently occurs alongside other cardiovascular and metabolic risk factors, including:
- High blood pressure
- Unhealthy cholesterol or triglyceride levels
- Excess abdominal fat
- Metabolic syndrome
Prediabetes itself is also associated with increased cardiovascular risk.
This means a prediabetes diagnosis should prompt a broader look at your health rather than focusing only on one glucose number.
Your healthcare provider may evaluate your blood pressure, cholesterol, triglycerides, weight, smoking status, physical activity and other cardiovascular risk factors as part of your overall care.
What Should You Do If You Have Prediabetes?
Finding out that you have prediabetes can be unsettling, but it gives you something extremely valuable: time to act.
You do not have to change everything at once.
The goal is to identify changes you can realistically maintain.
Improve the Overall Quality of Your Diet
There is no single “prediabetes diet” that everyone must follow.
A healthy eating pattern generally emphasizes foods such as:
- Non-starchy vegetables
- Whole fruits
- Beans and lentils
- Whole grains
- Lean sources of protein
- Nuts and seeds
- Healthy sources of fat
It can also help to reduce sugary drinks, heavily refined carbohydrates, and highly processed foods that provide large amounts of calories or rapidly digested carbohydrates with relatively little nutritional value.
Carbohydrate quality and quantity both matter. Understanding the glycemic index and diabetes can help you compare carbohydrate foods, but GI should be used as one tool rather than the sole basis for choosing what to eat.
Become More Physically Active
Physical activity can improve insulin sensitivity and help your muscles use glucose.
For many adults, a common goal is at least 150 minutes of moderate-intensity physical activity per week, spread across several days.
That might include:
- Brisk walking
- Cycling
- Swimming
- Dancing
- Other activities that raise your heart rate
Resistance training can also be valuable because muscle tissue uses glucose and plays an important role in metabolic health.
If you are currently inactive, you do not need to reach 150 minutes immediately. Starting with shorter periods of activity and gradually increasing them can be much more manageable.
Work Toward a Healthy Weight if Needed
If you have overweight or obesity, losing a relatively modest amount of weight can substantially reduce your risk of progressing to type 2 diabetes.
The landmark Diabetes Prevention Program showed that an intensive lifestyle program targeting approximately 7% weight loss and at least 150 minutes of physical activity per week substantially reduced the development of type 2 diabetes in people at high risk.
You do not need to achieve an “ideal” body weight to benefit.
Even modest, sustainable changes can improve insulin sensitivity and metabolic health.
Get Enough Sleep
Sleep is sometimes overlooked when people think about blood sugar.
Poor or insufficient sleep can affect appetite, hormones, insulin sensitivity and other aspects of metabolic health.
Try to maintain a consistent sleep schedule and address persistent sleep problems with your healthcare provider, particularly if you have symptoms of sleep apnea such as loud snoring or excessive daytime sleepiness.
Avoid Smoking
Smoking is associated with a greater risk of insulin resistance, type 2 diabetes and cardiovascular disease.
If you smoke, quitting is one of the most important steps you can take for your overall health.
Follow Up With Your Healthcare Provider
Prediabetes should not be treated as a one-time abnormal blood test that you simply forget about.
Follow-up allows you and your healthcare provider to see whether your glucose is improving, remaining stable or moving toward the diabetes range.
People with prediabetes are generally tested for type 2 diabetes at least annually.
Do You Need Medication for Prediabetes?
Not everyone with prediabetes needs medication.
Lifestyle intervention remains a cornerstone of reducing the risk of type 2 diabetes.
However, medication can be appropriate for some people at particularly high risk.
Metformin has the strongest evidence among medications used to help prevent or delay progression to type 2 diabetes in people with prediabetes.
Current recommendations suggest considering metformin particularly for higher-risk adults, including some people who are younger, have a higher BMI, have higher fasting glucose or A1C levels within the prediabetes range, or have a history of gestational diabetes.
Whether medication is appropriate depends on your individual risk factors and medical history.
Do not start diabetes medication or supplements on your own to treat prediabetes. Discuss your options with your healthcare provider.
What Questions Should You Ask Your Doctor?
If you’ve recently learned that you have prediabetes, useful questions include:
- Which test showed that I have prediabetes?
- What was my A1C or glucose result?
- How close am I to the diabetes range?
- Should the test be repeated?
- How often should I have my blood sugar checked?
- Which risk factors are most important for me?
- Would losing weight improve my risk?
- What changes to my eating habits would help most?
- How much physical activity is appropriate for me?
- Should I see a registered dietitian or diabetes care and education specialist?
- Should medication such as metformin be considered in my situation?
The answers will depend on your individual health, so your plan may look different from someone else’s.
Frequently Asked Questions
Is prediabetes considered diabetes?
No. Prediabetes means your glucose is higher than normal but has not reached the diagnostic range for diabetes. It does, however, increase your risk of eventually developing type 2 diabetes.
What A1C level means you have prediabetes?
An A1C from 5.7% through 6.4% is considered within the prediabetes range. An A1C of 6.5% or higher falls within the diabetes range, although diagnosis generally requires appropriate confirmation when there are no unequivocal symptoms of hyperglycemia.
What fasting blood sugar indicates prediabetes?
A fasting plasma glucose level from 100 through 125 mg/dL is within the prediabetes range. A result of 126 mg/dL or higher falls within the diabetes range and generally requires confirmation when there are no unequivocal symptoms.
Can you have prediabetes and feel completely normal?
Yes. Most people with prediabetes have no obvious symptoms. That is why screening is important, particularly if you have risk factors.
How serious is prediabetes?
Prediabetes should be taken seriously because it increases your risk of type 2 diabetes and is associated with cardiovascular and other metabolic risks. But it also provides an opportunity to intervene before diabetes develops.
Can prediabetes go away?
Blood glucose can improve enough that your results no longer fall within the prediabetes range. Maintaining the habits that produced that improvement remains important because your underlying risk of developing type 2 diabetes may still be higher.
Do I need to check my blood sugar at home if I have prediabetes?
Not everyone with prediabetes needs routine home glucose monitoring. Your healthcare provider can tell you whether home testing would provide useful information in your particular situation.
Can prediabetes be diagnosed with a home glucose meter?
No. A home glucose meter can provide useful glucose readings, but it should not be used by itself to diagnose prediabetes or diabetes. Diagnosis is based on appropriate blood testing interpreted by a healthcare professional.
Final Thoughts
Prediabetes is not diabetes, but it is an important sign that your body is having more difficulty keeping blood glucose within the normal range.
And because prediabetes usually causes no symptoms, knowing your numbers matters.
If your A1C or blood glucose falls within the prediabetes range, focus on what you can do next rather than assuming type 2 diabetes is inevitable.
Improving the quality of your diet, becoming more physically active, managing your weight when appropriate, getting adequate sleep, avoiding smoking, and following up with your healthcare provider can all contribute to lowering your risk.
For some people, medication may also be appropriate.
Most importantly, use a prediabetes diagnosis as an opportunity to understand your health better and make changes while there is still time to reduce your risk of developing type 2 diabetes.