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Pre-Diabetes (Hyperglycemia)

Alternative names: Glucose Intolerance, Hyperglycemia, Impaired Fasting Glucose, Impaired Glucose Tolerance, Prediabetes

What is pre-diabetes?
What are the signs of pre-diabetes?
What causes pre-diabetes?
How does my doctor tell if I have pre-diabetes?
How is pre-diabetes treated?

What is pre-diabetes?

Pre-diabetes is a condition in which a person's blood sugar (glucose) levels are higher than normal, but not high enough to be classified as diabetes. A person with pre-diabetes is at risk of developing type 2 diabetes. However, by making some lifestyle changes, a person with pre-diabetes can reduce his or her risk of developing type 2 diabetes.

What are the signs of pre-diabetes?

Most people with pre-diabetes have no symptoms. Because of this, many doctors recommend that overweight people age 45 or older be tested for pre-diabetes. People under age 45 who have a Body Mass Index (BMI) of 25 or more, as well as some risk factors for pre-diabetes, should also be tested.

In addition to the danger of developing diabetes, people with pre-diabetes have an increased risk of heart and blood vessel (cardiovascular) disease.

What causes pre-diabetes?

Insulin is a protein hormone that regulates the body's blood sugar levels. In pre-diabetes – as in type 2 diabetes – a person's body can't use insulin effectively. This means that glucose (sugar) builds up in the blood instead of being used by the body as fuel.

Risk factors that increase a person's chances of developing pre-diabetes include:

  • Being overweight, or obese
  • Being inactive
  • Having a family history of diabetes
  • Having a history of gestational diabetes, or giving birth to a baby weighing more than nine pounds
  • Having high blood pressure
  • Having low levels of "good" (HDL) blood cholesterol, and high triglyceride levels
  • Ethnic background. People of certain races are more likely to get pre-diabetes, including African-Americans, Hispanics, Native Americans, Asian-Americans, and Pacific Islanders.

How does my doctor tell if I have pre-diabetes?

Tests that check the levels of sugar (glucose) in your blood can help your doctor diagnose pre-diabetes. Two common tests include a fasting plasma glucose test and an oral glucose tolerance test.

In the fasting plasma glucose test, the patient eats or drinks nothing except water for eight hours. Blood is then drawn and tested. This test is usually performed in the morning. In the oral glucose tolerance test, the patient drinks a glucose solution. Blood is then drawn two hours later, and tested.

Normal blood sugar levels for the fasting plasma glucose test are below 100 mg/dl (milligrams of glucose per deciliter of blood). A person with pre-diabetes has a fasting blood glucose level between 100 and 125 mg/dl. A person with a fasting blood glucose level above 125 mg/dl has diabetes.

Normal blood sugar levels for the oral glucose tolerance test are below 140 mg/dl. A person with blood sugar levels between 140 and 199 mg/dl has pre-diabetes. A person with a blood sugar level above 199 mg/dl has diabetes.

If a test shows that you have pre-diabetes, your doctor will order a follow-up test on another day to confirm the diagnosis. People with pre-diabetes should be tested every one or two years to monitor their condition. People at risk for pre-diabetes, but with normal test results, should be tested every three years.

How is pre-diabetes treated?


If you have been diagnosed with pre-diabetes, you can make changes to your exercise and eating habits to prevent or delay the onset of type 2 diabetes. Such changes may include:

  • Reduce your weight by five to ten percent
  • Perform modest exercise for thirty minutes every day. This can be as simple as taking a walk, raking leaves, or riding a stationary bicycle.
  • Switch to a diet that is low in saturated fat and high in fiber
  • Quit smoking, if you smoke
  • Talk to your doctor about ways to reduce high blood pressure and/or cholesterol levels


In some cases, a doctor may prescribe metformin (Glucophage), to help lower blood sugar levels.

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