Prediabetes

Overview

Prediabetes is a warning stage in which blood sugar levels are higher than normal but not yet high enough to be classified as type 2 diabetes. It develops when the body becomes less able to use insulin effectively (insulin resistance), so glucose builds up in the blood.

Prediabetes matters because it signals a substantially increased risk of developing type 2 diabetes, as well as heart disease and stroke. Importantly, it is often reversible. With changes to diet, weight, and physical activity, many people can bring their blood sugar back to a healthy range or at least delay progression to diabetes. Because prediabetes usually causes no symptoms, it is frequently discovered only through a blood test, which is why screening is recommended for people at risk.

Symptoms

Prediabetes usually causes no noticeable symptoms, which is why so many people are unaware they have it. When changes do appear, they overlap with early type 2 diabetes and may include:

• Increased thirst
• Frequent urination
• Increased hunger
• Fatigue
• Blurred vision

Some people develop darkened, velvety patches of skin in body folds such as the neck, armpits, or groin (acanthosis nigricans), a sign of insulin resistance. Because symptoms are often absent, blood testing is the only reliable way to detect prediabetes.

Causes

Prediabetes develops from a combination of insulin resistance and a relative shortfall in insulin's effect:

• Insulin resistance: The body's cells respond less well to insulin, so the pancreas must make more to keep blood sugar normal, and eventually it cannot keep up.
• Excess body weight: Especially fat around the abdomen, which strongly promotes insulin resistance.
• Physical inactivity: Less activity reduces the muscles' use of glucose.
• Genetics and family history: A family history of type 2 diabetes increases risk.

Other factors, such as a history of gestational diabetes and polycystic ovary syndrome, also raise the likelihood of developing prediabetes.

Risk Factors

• Being overweight or having excess abdominal fat
• Physical inactivity
• Age 45 or older
• A family history of type 2 diabetes
• A history of gestational diabetes or having a large baby
• High blood pressure or abnormal cholesterol
• Polycystic ovary syndrome
• Certain ethnic backgrounds with higher diabetes risk

Diagnosis

Prediabetes is diagnosed with blood tests that measure blood sugar:

• A1C test: Reflects average blood sugar over about three months; 5.7% to 6.4% indicates prediabetes.
• Fasting plasma glucose: 100 to 125 mg/dL after an overnight fast indicates prediabetes.
• Oral glucose tolerance test: A blood sugar of 140 to 199 mg/dL two hours after a sugary drink indicates prediabetes.

Because there are no reliable symptoms, screening is recommended for adults with risk factors, and abnormal results are usually confirmed with a repeat test.

Treatment

The cornerstone of managing prediabetes is lifestyle change, which is highly effective at preventing or delaying type 2 diabetes:

• Weight loss: Losing even a modest amount of body weight can substantially lower risk.
• Regular physical activity: Aiming for about 150 minutes of moderate activity per week, such as brisk walking.
• Healthier eating: More vegetables, whole grains, and fiber, with less added sugar, refined carbohydrates, and processed food.
• Medication: In some people at higher risk, metformin may be prescribed to help prevent progression.

Structured programs such as diabetes prevention programs combine these steps and have a strong track record. Regular follow-up testing tracks progress.

Prevention

• Maintain a healthy weight and lose excess weight if needed
• Be physically active most days of the week
• Eat a diet rich in vegetables, whole grains, and lean protein, limiting sugary drinks and processed foods
• Do not smoke
• Get screened for blood sugar if you have risk factors
• Manage blood pressure and cholesterol

When to See a Doctor

Ask your doctor about blood sugar screening if you have risk factors such as excess weight, inactivity, or a family history of diabetes. See a doctor if you develop:

• Increased thirst, frequent urination, or unexplained fatigue
• Blurred vision
• Darkened patches of skin in body folds

If you have been told you have prediabetes, regular follow-up is important to monitor your blood sugar and adjust your plan, since early action can prevent or delay type 2 diabetes.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Prediabetes.
2. American Diabetes Association (ADA). Diagnosis and classification.
3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Prediabetes & insulin resistance.
4. MedlinePlus, U.S. National Library of Medicine. Prediabetes.