Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at March 21, 2016

Prediabetes is a condition where blood sugar, or glucose, levels are above normal, but not yet to the point of being diagnosed as diabetes. Doctors often refer to prediabetes as IGT, standing for impaired glucose tolerance.


Definition & Facts

According to the American Diabetes Association, prediabetes places patients at a greater risk for developing type-2 diabetes and can lead to other kinds of cardiovascular disease. Without intervention, prediabetes will often become type-2 diabetes within 10 years. However, the progression of prediabetes to type-2 diabetes can often be stopped with proper lifestyle changes.

Symptoms & Complaints

Prediabetes often has no symptoms in its early stages. One possible sign of the condition is darkened areas of skin, called acanthosis nigricans, around the neck, in the armpits and on the elbows, knuckles, and knees. Polycystic ovary syndrome, a condition typically characterized by irregular menstrual periods, obesity, and excess hair growth may also be a sign of prediabetes.

People with high-risk factors, such as a family history of type-2 diabetes, inactive, being overweight and a prior diagnosis of gestational diabetes should consult a physician. Some classic red flags of the latter stages of prediabetes, just before progressing to type-2 diabetes, include:


While the exact cause of prediabetes isn't known, genetic factors appear to be key. Researchers have found that some genes are connected to insulin resistance. Excess fat, especially in the abdominal area, is an important factor in the development of prediabetes.

Research shows that patients with prediabetes have lost the ability to process dietary sugar properly. This results in sugar remaining in the bloodstream, rather than doing its intended job of providing energy to the cells. Most of the body's glucose comes from foods, specifically those foods high in carbohydrates. Any food that is made up of carbohydrates can have an effect on blood-sugar levels, not only sweet-tasting foods.

During digestion, when sugar enters the bloodstream, the pancreas releases the hormone insulin. Insulin allows the cells to absorb the glucose, where it is utilized as a source of energy. As blood-sugar levels decline, the pancreas reduces insulin secretion. When prediabetes occurs, the insulin-secretion process has stopped work properly, either by the pancreas not producing enough insulin or the cells becoming resistant to insulin, or a combination of both.

Diagnosis & Tests

The American Diabetes Association urges blood-glucose screening starting at age 45, or earlier for patients who have a body-mass index over 25 or other risk factors. Tests used to diagnose prediabetes typically include:

Glycated hemoglobin, also referred to as an A1C test, measures the average blood-glucose level for the past eight to 12 weeks by reading the percentage of blood glucose attached to hemoglobin molecules, the proteins in red blood cells that carry oxygen. A normal A1C reading is below 5.7 percent, whereas readings between 5.7 and 6.4 percent is an indication of prediabetes and a reading of over 6.4 percent on two individual tests indicates the condition has progressed to diabetes. Certain conditions can cause the A1C test to be inaccurate, such as a patient with an uncommon hemoglobin variant or pregnancy.

Fasting blood sugar test measures a blood sample taken after the patient has fasted for a minimum of eight hours. A blood-glucose level under 100 milligrams per deciliter is considered normal, a reading of 100 to 125 milligrams per deciliter means prediabetes is present and a blood-sugar level of 126 milligrams per deciliter or higher usually indicates diabetes.

Oral glucose tolerance test is usually only used during pregnancy. A blood sample is taken after fasting for at least eight hours, a sugary solution is given orally and then blood sugar is measured again in two hours. A blood-glucose reading of less than 140 milligrams per deciliter is normal, a reading between 140 and 199 milligrams per deciliter is considered prediabetes and a reading above of 200 milligrams per deciliter typically indicates diabetes.

Treatment & Therapy

The best treatment for prediabetes is creating healthy lifestyle choices like achieving and maintaining a healthy weight, adopting a healthy diet, and getting regular exercise. These steps are often enough to bring blood-glucose levels back to with normal ranges, or at least keep the condition from progressing to type-2 diabetes. Recommendations include:

  • Choosing a diet high in fiber with low-sugar and low-fat foods, such as the “Mediterranean” diet that places an emphasis on vegetables, fruits, whole grains and fish.
  • Daily physical activity with 30 to 60 minutes of moderate activity, such as a brisk walk, swimming laps or riding a bicycle, four or more days per week. The American Diabetes Association also recommends adding some form of resistance training, like weightlifting, at least twice a week.
  • Losing just five to 10 percent of excess body weight can substantially reduce the risk of prediabetes becoming full-blown diabetes.

However, even these steps may not always be enough to prevent prediabetes from progressing to type-2 diabetes. In some cases the oral diabetes drug metformin may be prescribed by a doctor for patients at high risk. Medications to control high blood pressure and high cholesterol may also be prescribed.

Prevention & Prophylaxis

The same three-part strategy of lifestyle changes that are used to treat, or even reverse, prediabetes are also the best prevention. While only roughly 25 percent of patients with prediabetes will develop full-blown diabetes in the short term, in three to five years, that percentage rises drastically over the long term for those who do not take action.