What Is Prediabetes?

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Prediabetes is a condition that does not typically cause symptoms. But it is a concern because it is a precursor to type 2 diabetes. Without intervention, it can progress to the disease, putting you at risk for a host of related complications.

Prediabetes is diagnosed with blood tests that measure blood sugar and metabolic parameters. There are well-established strategies for treating prediabetes and preventing type 2 diabetes. Dietary management, weight loss, and exercise are often effective, though medication is sometimes also needed.

Prediabetes is also known as impaired glucose tolerance or impaired fasting glucose.

prediabetes symptoms
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Prediabetes Symptoms

Prediabetes generally affects adults between 40 and 60.

The condition tends to be silent, rarely causing any noticeable symptoms. In fact, according to the Centers for Disease Control and Prevention (CDC), approximately more than one in three adults in the United States has prediabetes. Of them, 84% do not know it.

Because of the lack of symptoms, most people—once diagnosed—do not know exactly when their prediabetes began. The condition can remain stable for years before progressing to diabetes.

In the rare instances when prediabetes does cause symptoms, they usually are subtle and can easily be missed or mistaken for other health issues.

Signs of prediabetes include:

  • Excessive hunger or thirst
  • Weight gain
  • Fatigue
  • Polyuria (frequent urination caused by increased fluid intake to relieve thirst)

Complications

Without treatment, prediabetes progresses to type 2 diabetes, a medical condition that causes a number of health complications, including:

Prediabetes is not associated with either type 1 diabetes, a form that usually affects young children, or diabetes insipidis, a condition that affects the kidneys.

Causes

Prediabetes occurs when cells in the body become resistant to insulin, a hormone produced by the pancreas. It keeps blood sugar levels within a healthy range by helping the cells in the body store glucose. Eventually, the cells convert glucose into energy.

If you have prediabetes, you probably make enough insulin, but the cells of your body are resistant to insulin and its effects. This results in a slightly elevated blood glucose level, as well as decreased energy.

Risk Factors

There are several risk factors associated with prediabetes, but the exact cause of the condition is not known. People who don't get much physical activity may be at risk of prediabetes.

Hypertension, high cholesterol levels, obesity, and excess body fat, particularly in the abdominal area, are associated with prediabetes. It is not clear whether these health problems cause or are caused by prediabetes, or whether they are all caused by another factor.

Associated Conditions

Several metabolic changes can take place before prediabetes develops.

Insulin resistance is a condition that begins before prediabetes, and it might not cause high blood sugar.

A similar condition called metabolic syndrome is characterized by an elevated body mass index (BMI), hypertension, high cholesterol, and insulin resistance.

Diagnosis

Because prediabetes typically does not cause symptoms, it usually is detected during routine screening for diabetes. The American Diabetic Association (ADA) recommends adults begin being screened at age 45.

The ADA also advises testing for adults who:

  • Have a high BMI and one or more other risk factors for diabetes: High BMI is defined as 25 kg/m2 for everyone except Asian Americans, for whom a high BMI is defined as 23kg/m2 or higher
  • Belong to a high-risk race or ethnic population: Specifically, these are African Americans, Latinos, American Indians, Alaska Natives, Asian Americans, and Pacific Islanders
  • Have a parent or sibling with a history of diabetes
  • Have had gestational diabetes (should test every three years)
  • Are physically inactive
  • Have hypertension (blood pressure is 140/90 mmHg or higher) or are taking medication to treat it
  • Have low levels of high-density lipoprotein (HDL) cholesterol or high levels of triglycerides
  • Have predisposing conditions, including acanthosis nigricans, non-alcoholic steatohepatitis, polycystic ovary syndrome, atherosclerotic cardiovascular disease, and obesity
  • Take certain medications (atypical antipsychotics or glucocorticoids)
  • Are HIV-positive

Screening Tests

Often with prediabetes, blood glucose is only mildly elevated, so it may take more than one type of blood test to definitively diagnose the condition.

The tests used to screen for prediabetes include:

  • Fasting blood sugar test: This test measures your blood sugar after you have gone without food for eight hours. Normal fasting glucose is below 100 mg/dl. Anything in the 100 to 126 mg/dl range suggests prediabetes; a level above 126 mg/dl suggests diabetes.
  • Glucose tolerance test: This test measures your blood glucose level before and after you drink a carbohydrate drink. A normal glucose level after drinking a 75 gm glucose load is less than 140 mg/dl. A 140 to 199 mg/dl result indicates prediabetes, and 200 mg/dl or more indicates diabetes.
  • A1C test: Glucose glycates (sticks) to hemoglobin A, a protein found in red blood cells. Once it does, the glucose remains there for the lifespan of the hemoglobin A protein, which can be as long as 120 days. The A1C test measures what percentage of hemoglobin A proteins are glycated. For example, an A1C of 7% means that 7% of hemoglobin A proteins are glycated. In doing this, it tells you your average blood sugar levels for the previous two to three months.

Prediabetes is diagnosed when an A1C test is in the range of 5.7 % to 6.4 %. Anything under 5.7 % is regarded as normal. An A1C of 6.5 % or higher is considered diabetes.

Glucose Monitoring

While it is not required for prediabetes, some people choose to regularly monitor glucose at home. This can help you keep track of how well your treatment plan is working.

There are many easy-to-use glucose monitors, including options that continuously monitor glucose levels.

Treatment

Treating prediabetes focuses on lifestyle modifications aimed at preventing the condition from progressing to type 2 diabetes.

It's important to be consistent in making these changes; regular medical appointments and glucose monitoring can help keep you on track.

Measures you can take to manage prediabetes include:

  • Losing weight: Even modest weight loss—5% to 10% of your body weight—can prevent or delay the progression to diabetes.
  • Reducing your carbohydrate intake: Carbs impact blood sugar more than other macronutrients. It's especially important to avoid refined carbs, such as white bread, pasta, rice, and snack foods. It is also helpful to eliminate juice and other sweetened beverages, and to increase your 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.
  • Being more active: Exercise not only helps keep weight in check, it helps the body better use insulin. Physical activity (along with weight loss) can help cut your risk for diabetes by nearly 60%.

If lifestyle changes aren't effective, your healthcare provider might recommend medication such as Glucophage (metformin) to help manage your blood sugar. This medication has been shown to help prevent the development of type 2 diabetes.

​A Word From Verywell

If you have any risk factors for diabetes, it is important to be screened. If your tests show signs of prediabetes, simple lifestyle changes—weight loss, exercise, a diet low in sugar and unhealthy fats and rich in nutrients—are often enough to prevent diabetes and will improve your overall health and well-being as well.

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