An Overview of Prediabetes

Woman checking her blood glucose using her glucose meter

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Prediabetes sometimes called impaired glucose tolerance or impaired fasting glucose, is a condition in which the cells in the body are becoming resistant to insulin or the pancreas is not producing normal amounts of insulin, causing elevated levels of glucose (sugar) in the blood. It's a warning sign that a person may be on track for developing type 2 diabetes (not to be confused with type 1 diabetes, or diabetes mellitus, which is an autoimmune disease). Prediabetes also is associated with an increased risk of heart disease or stroke. Without intervention, prediabetes can progress to type 2 diabetes, typically within 10 years. Fortunately, treating prediabetes is relatively straightforward and typically just a matter of losing weight and making certain simple, straightforward lifestyle changes.


Prediabetes rarely causes obvious symptoms. In fact, according to the U.S. Centers for Disease Control and Prevention (CDC), of the approximately 84 million adults (more than 1 in 3) in the United States who have prediabetes, 90 percent don't even know it.

When prediabetes does cause symptoms, they easily can be mistaken for other health issues. Warning signs of prediabetes include:

  • Excessive hunger or thirst
  • Weight gain
  • Fatigue
  • Polyuria (frequent urination caused in large part by increases in fluid intake to relieve thirst)


Insulin is a hormone produced by the pancreas. It has two functions: convert glucose (the sugar derived from carbohydrates in the diet) into energy and keep blood sugar levels within a healthy range. Prediabetes typically develops because the body is becoming resistant to insulin and its effects.

Excess body fat, particularly in the abdominal area, is a common cause of insulin resistance and plays a major role in the development of prediabetes and diabetes. This is because belly fat can lead to insulin resistance in which certain cells (primarily within the muscles, liver, and fat tissue) do not use insulin properly.

People who have prediabetes (as well as type 2 diabetes, for that matter) still produce insulin, but their bodies can't use it the way they should. As a result, the body continues to make more insulin, thinking that it needs it, causing the pancreas to become overworked and eventually unable to produce normal amounts of the hormone.


Prediabetes is diagnosed using a blood test, such as a fasting blood sugar test (which is performed after going without food for eight hours), a two-hour plasma glucose test, or most often, an A1C test. This test measures average blood sugar levels for the previous two to three months. It works by looking at how much glucose sticks (glycates) to a protein found in red blood cells called hemoglobin A.

Once glucose sticks to a hemoglobin protein, it typically remains there for the lifespan of the hemoglobin A protein, which can be as many as 120 days. This means that, at any moment, the glucose attached to the hemoglobin A protein reflects the level of your blood sugar over the last two to three months.

The A1C test measures what percent of hemoglobin proteins are glycated. For example, a 7 percent A1C means that 7 percent of hemoglobin proteins are glycated.

Prediabetes is diagnosed when an A1C test is in the range of 5.7 percent to 6.4 percent. Anything under 5.7 percent is regarded as normal.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, people with certain risk factors should be screened for prediabetes. They include those who:

  • Are over 45: If results are normal, testing should be repeated a minimum of three-year intervals, with consideration of more frequent testing depending on initial results (e.g. those with prediabetes should be tested yearly)
  • Have a body mass index (BMI) of more than 25 kg/m2 or a waist circumference of more than 40 inches in men or 35 inches in women. The BMI cut-off for Asian Americans is lower (23kg/m2).
  • Belong to high-risk populations including African Americans, Hispanic/Latinos, American Indians, Alaska Natives, Asian Americans, Pacific Islanders
  • Have a parent or sibling with diabetes
  • Are mothers with a history of gestational diabetes or who have given birth to a baby weighing more 9 pounds
  • Are physically inactive
  • Have hypertension (high blood pressure that's equal or greater than 140/90 mmHg) or are on therapy for hypertension
  • Have low levels of high-density lipoprotein (HDL) cholesterol
  • Have high levels of triglycerides
  • Live with other conditions associated with insulin resistance such as acanthosis nigricans, non-alcoholic steatohepatitis, polycystic ovary syndrome, and atherosclerotic cardiovascular disease


Treating prediabetes is actually a matter of taking measures to prevent progression of the condition to type 2 diabetes. This largely is done through lifestyle modifications:

Weight loss: Studies have shown that even modest weight loss—5 percent to 7 percent of body weight—can prevent or delay the progression toward diabetes. For example, someone who weighs 200 pounds, can lower their risk of developing diabetes by losing just 10 pounds.

Reduction of carbohydrate intake: Carbohydrates are the nutrient that impacts blood sugar the most. The most important ones to avoid are those that are refined, such as white bread, pasta, rice, and snack foods. It also is helpful to eliminate juice and other sweetened beverages and to increase intake of non-starchy vegetables.

Following a Mediterranean diet: This means focusing on fruits, vegetables, and healthy fats, such as nuts, seeds, and olive oil.

Increase in physical activity: Exercise not only helps keep weight in check, but it also helps the body better utilize insulin. Being more physical can actually help cut your risk for diabetes by half.

​A Word From Verywell

It may be worrisome to discover you have prediabetes, so it can be helpful to regard the diagnosis as a wake-up call to live a more healthy life overall. Losing weight, exercising, following a nutrient-rich diet and cutting back on sugar and unhealthy fats will help to keep illness and conditions other than diabetes at bay. These measures also will increase your energy levels, help you to sleep better, and improve your mood. You can change your life for the better.

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