Prediabetes – What It Is, Why It Happens, and How to Manage It
What is Prediabetes?
Prediabetes is a metabolic condition in which blood‑glucose (sugar) levels are higher than normal but not yet high enough to be classified as type 2 diabetes. It is often called “borderline diabetes” because it signals that the body’s ability to regulate glucose is impaired. According to the Centers for Disease Control and Prevention (CDC), more than 96 million U.S. adults—about 1 in 3—have prediabetes, yet 84 percent are unaware of it.1
People with prediabetes have an elevated risk of developing full‑blown type 2 diabetes, heart disease, and stroke. The good news is that lifestyle changes and, in some cases, medication can reverse prediabetes and lower the risk of complications.
Common Causes
Prediabetes does not have a single cause; it usually results from a combination of genetic, environmental, and physiological factors. Below are the most common contributors:
- Insulin resistance: Body cells become less responsive to insulin, the hormone that moves glucose from the blood into cells.
- Weight gain/obesity: Excess body fat—especially around the abdomen—promotes insulin resistance.
- Physical inactivity: Sedentary lifestyles reduce the muscles’ ability to use glucose effectively.
- Family history of diabetes: Genetic predisposition raises risk.
- Age ≥45 years: Metabolism slows with age, increasing insulin resistance.
- Gestational diabetes history: Women who develop diabetes during pregnancy are at higher risk later.
- Polycystic ovary syndrome (PCOS): Hormonal imbalances often coexist with insulin resistance.
- Unhealthy diet: High intake of refined carbohydrates, sugary drinks, and saturated fats.
- Certain medications: Corticosteroids, some antipsychotics, and HIV protease inhibitors can raise blood glucose.
- Sleep disorders: Chronic sleep deprivation or obstructive sleep apnea worsens insulin resistance.
Associated Symptoms
Prediabetes is frequently called a “silent” condition because many people experience no noticeable symptoms. However, some individuals notice subtle changes that may accompany elevated glucose levels:
- Increased thirst or dry mouth
- Frequent urination, especially at night
- Unexplained fatigue or sluggishness
- Blurred vision
- Darkened patches of skin, typically on the neck or armpits (acanthosis nigricans)
- Slow healing of cuts or infections
If any of these signs appear, it is worthwhile to have blood‑glucose testing performed.
When to See a Doctor
Because prediabetes can be asymptomatic, routine screening is essential—especially if you have risk factors. You should schedule a medical visit if you:
- Are 45 years old or older and have never been screened.
- Have a BMI ≥ 25 kg/m² (≥ 23 kg/m² for Asian‑origin individuals) and at least one additional risk factor.
- Experience any of the associated symptoms listed above.
- Have a family history of type 2 diabetes.
- Had gestational diabetes or gave birth to a baby weighing > 9 lb (4 kg).
Early detection allows you and your health‑care team to intervene before the condition progresses.
Diagnosis
Doctors use several laboratory tests to determine whether someone has prediabetes. The most common are:
- Fasting Plasma Glucose (FPG): Blood drawn after an overnight fast. Prediabetes is diagnosed when FPG is 100‑125 mg/dL (5.6‑6.9 mmol/L).2
- Oral Glucose Tolerance Test (OGTT): Measures glucose 2 hours after consuming a 75‑g glucose solution. Values of 140‑199 mg/dL indicate prediabetes.
- Hemoglobin A1c (HbA1c): Reflects average blood glucose over the past 2‑3 months. Results of 5.7‑6.4 % are diagnostic for prediabetes.3
- Random plasma glucose: Used less often, but a level of 140‑199 mg/dL with symptoms may also suggest prediabetes.
Most guidelines recommend confirming the diagnosis with a repeat test on a separate day, especially when results are borderline.
Treatment Options
Lifestyle Modifications (First‑Line)
Extensive research—including the landmark Diabetes Prevention Program (DPP)—shows that modest weight loss and increased activity can reduce diabetes risk by 58 % (71 % in participants ≥ 60 years).4
- Weight loss: Aim for 5‑10 % of body weight (e.g., 10 lb for a 200‑lb individual).
- Physical activity: At least 150 minutes/week of moderate‑intensity aerobic exercise (brisk walking, cycling) plus resistance training two days per week.
- Dietary changes:
- Adopt a Mediterranean‑style or DASH (Dietary Approaches to Stop Hypertension) eating pattern.
- Prioritize whole grains, legumes, fruits, vegetables, nuts, and lean proteins.
- Limit sugary beverages, processed snacks, refined carbs, and saturated fats.
- Consider portion control tools such as MyPlate or a calorie‑tracking app.
- Sleep hygiene: 7‑9 hours/night; treat sleep apnea if present.
- Stress management: Mindfulness, yoga, or counseling can improve insulin sensitivity.
Medication
Medication is not required for everyone with prediabetes, but it may be recommended for those at very high risk (e.g., BMI ≥ 35 kg/m², age ≥ 60, or previous gestational diabetes). Options include:
- Metformin: An oral biguanide that improves insulin sensitivity. The DPP showed a 31 % risk reduction in participants taking metformin, especially younger and more overweight individuals.5
- GLP‑1 receptor agonists (e.g., liraglutide): Emerging data suggest they aid weight loss and glucose control, but cost and insurance coverage can be limiting.
Medication should always be paired with lifestyle changes and monitored by a health‑care provider.
Monitoring
Even without medication, regular follow‑up is crucial. The typical schedule is:
- HbA1c or fasting glucose every 6‑12 months.
- Weight and waist‑circumference checks at each visit.
- Blood pressure and lipid profile annually (prediabetes often coexists with dyslipidemia).
Prevention Tips
If you are at risk but do not yet have prediabetes, these strategies can help keep your blood sugar in the normal range:
- Maintain a healthy weight: Even a modest 5 % reduction can dramatically improve insulin sensitivity.
- Move more: Take the stairs, park farther from store entrances, or use a standing desk.
- Choose fiber‑rich carbs: Whole grains, beans, and vegetables slow glucose absorption.
- Limit sugary drinks: Replace soda or sweetened coffee with water, herbal tea, or unsweetened sparkling water.
- Eat protein with every meal: Helps stabilize post‑meal glucose spikes.
- Stay hydrated: Dehydration can falsely raise glucose concentrations.
- Regular health checks: Annual screening for those over 45 or with risk factors.
- Quit smoking: Smoking worsens insulin resistance and cardiovascular risk.
Emergency Warning Signs
- Severe nausea, vomiting, or abdominal pain accompanied by high blood glucose (> 250 mg/dL) – possible hyperglycemic crisis.
- Sudden, marked weakness, confusion, slurred speech, or loss of consciousness – may indicate dangerously low blood sugar (hypoglycemia) if medication is being used.
- Rapid breathing, fruity‑smelling breath, or extreme dehydration – signs of diabetic ketoacidosis (DKA), a rare but life‑threatening condition.
Call 911 or go to the nearest emergency department if any of these occur.
Bottom Line
Prediabetes is a wake‑up call that your body’s glucose regulation is under stress. The condition is highly prevalent but also highly modifiable. By understanding the risk factors, undergoing appropriate testing, and committing to evidence‑based lifestyle changes—sometimes supplemented with medication—you can often return blood‑glucose levels to the normal range and dramatically lower the chance of developing type 2 diabetes, heart disease, and stroke.
Key References
- Centers for Disease Control and Prevention. Prediabetes – About. Accessed June 2026.
- American Diabetes Association. Standards of Care in Diabetes—2022. Diabetes Care. 2022.
- Mayo Clinic. Prediabetes Diagnosis. Updated 2023.
- Diabetes Prevention Program Research Group. Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. N Engl J Med. 1999.
- U.S. National Library of Medicine. Metformin for Prevention of Diabetes in High‑Risk Populations. JAMA. 2015.