Prediabetes, also known as borderline diabetes, is where a person’s blood sugar levels are higher than usual but not yet high enough for a diagnosis of type 2 diabetes.

Prediabetes is a condition that can progress to type 2 diabetes. Doctors may also refer to prediabetes as impaired glucose tolerance or impaired fasting glucose.

Research suggestsTrusted Source that this progression occurs in about 25% of people with prediabetes within 3 to 5 years. Overall, up to 70% of people with prediabetes will develop diabetes at some point in their life.

An elderly male sitting on a sofa with a doctor, who is explaining something and pointing to tablet.Share on Pinterest
The Good Brigade/Getty Images

Prediabetes does not alwaysTrusted Source have symptoms. Many people may not know they have it until a doctor determines they have high blood sugar based on a blood test or a complication occurs.

If symptoms do occur, they may include:

However, most people will not know they have prediabetes until they undergo testing.

According to the National Institute of Diabetes and Digestive and Kidney DiseasesTrusted Source, various other conditions and factors can increase the risk of prediabetes, including:

Regularly consuming sugary drinks may also increase the risk. A 2021 review associates drinks with added sugar, including soda, juices, and sweetened tea or coffee, with a higher risk of diabetes.

Anyone with any of these risk factors may benefit from a prediabetes screening to check whether they have the condition.

A doctor may use the following blood tests to diagnose or screen for prediabetes:

  • Glucose tolerance test: A glucose tolerance test measures how quickly the body can process the sugar in the blood in a 2-hour period.
  • Fasting blood test: A fasting blood test measures blood sugar levels after a person has not eaten for a specific period.
  • Hemoglobin A1C test: An A1C test measures the average blood sugar levels over 2 or 3 months. People do not need to fast or take any special liquids or medications for the A1C test, and it gives reliable results.
  • Random plasma blood test: This measures a person’s blood sugar levels at any time.

The American Diabetes Association states that a doctor will diagnose prediabetes when test results show the following measurements:

  • fasting blood sugar levels of 100 to 125 milligrams per deciliter (mg/dl)
  • glucose tolerance levels of 140 to 200 mg/dl
  • an A1C test result of 5.7% to 6.4%

A doctor may also re-test these levels to confirm that the readings are not due to one-off spikes in blood sugar.

Who should undergo screening for prediabetes?

Healthcare professionals may recommend that people start to undergo screening for prediabetes between the ages of 30 and 45Trusted Source, repeating the screening every 3 years.

People with risk factors may need to start screening earlier and get follow-ups more often than this.

The Centers for Disease Control and Prevention (CDC) offers an online testTrusted Source to assess people’s risk of prediabetes.

Anyone who is concerned they may have prediabetes should also visit a doctor for testing and a diagnosis.

Prediabetes is reversible. Lifestyle changes and weight management are theTrusted Source first-line treatment option.

Healthcare professionals may suggest a person work toward a goal of exercising for 30 minutes per day and switch to a low fat diet, with the aim of reducing their weight by 7%.

If someone has a high risk of type 2 diabetes or cannot make the necessary lifestyle changes, doctors may suggest management with medication. Medications may include metformin (Glucophage) and acarbose (Prandase).

Managing prediabetes may also involve continual monitoring of the risk factors and regular testing of blood sugar levels.

National Diabetes Prevention Program

The CDC leads a program called the National Diabetes Prevention ProgramTrusted Source, which aims to help people with prediabetes lower their risk of type 2 diabetes by building new lifestyle habits.

The program runs for a year and involves:

  • a lifestyle coach keeping people motivated, helping them set and meet goals
  • a CDC-approved curriculum with handouts, lessons, and more
  • a support group of people with similar goals

The program may teach a person about the following:

  • balanced eating
  • physical activity
  • managing stress
  • getting back on track if new habits are difficult to maintain
  • overcoming challenges, such as choosing healthy foods when eating out or during holidays

A lifestyle coach can work with people to make sure the sessions suit their needs, interests, and background.

The following actions may helpTrusted Source a person prevent prediabetes:

  • exercising regularly
  • eating a balanced diet with plenty of fiber
  • maintaining a moderate weight for their body type
  • taking any medications that a doctor prescribes
  • quitting smoking, if applicable

A healthcare professional may also recommend that people limit the amount of salt, added sugar, and carbohydrates in their diet.

Around 70%Trusted Source of people with prediabetes progress to a diagnosis of diabetes. However, the rate of progression may vary from person to person, and not all people with prediabetes will progress to diabetes.

People may be able to prevent this progression if they make appropriate lifestyle changes. It is important for people with prediabetes to work with a healthcare professional to lower their risk of progression and complications.

What foods should someone with prediabetes eat?

Healthcare professionals may recommend that people with prediabetes eat a balanced diet with plenty ofTrusted Source fiber. Fiber-rich foods includeTrusted Source whole grains, beans, and leafy green vegetables.

People may also benefit from limiting simple carbs, salt, and added sugar.

What are the complications of prediabetes?

Even if it does not progress to type 2 diabetes, prediabetes can leadTrusted Source to complications such as stroke, kidney failure, and heart disease.

Can children have prediabetes?

In a 2019 studyTrusted Source involving 5,786 people, 18% of the 2,606 adolescent participants — ages 12 to 18 years — had prediabetes. Among the 3,180 young adults, the prevalence was 24%.

Many childrenTrusted Source who develop type 2 diabetes do not receive a diagnosis until adolescence. This is, in part, because puberty hormones can make it harder for the body to regulate insulin.

Parents and caregivers can help prevent diabetes in children by encouraging them to eat a balanced diet and engage in plenty of physical activity.

Can prediabetes progress to type 1 diabetes?

Prediabetes refers to a metabolic state that is a precursor to type 2 diabetes. It cannot evolve into type 1 diabetes.

However, there is researchTrusted Source on a parallel disease called pre-type 1 diabetes, in which a person’s immune system displays certain characteristics that indicate progression to type 1 diabetes.

How long does it take to reverse prediabetes?

With a well-balanced diet, regular exercise, and prescribed medical interventions, a person may be able to reverse prediabetes in about 3 yearsTrusted Source.

Prediabetes is the stage before type 2 diabetes develops. It does not usually cause active symptoms, and most people will not be aware that they have the condition until it progresses to diabetes and starts causing health problems.

Anyone who is at risk of developing diabetes should have regular screening. Risk factors include high blood pressure, low levels of physical activity, and overweight or obesity.

Prediabetes can be reversible with a sustained exercise program and a balanced diet. People may also be able to join a diabetes prevention program.