What Is Prediabetes?
Prediabetes is a condition in which your blood sugar levels are higher than normal, but not yet high enough to be diagnosed as type 2 diabetes. Think of it as a warning stage. Your body is starting to struggle with blood sugar control, but there is still time to turn things around.
To understand prediabetes, it helps to know how blood sugar normally works. When you eat, your body breaks down food into glucose, which enters your bloodstream. Your pancreas then releases a hormone called insulin, which acts like a key that unlocks your cells so glucose can enter and be used for energy.
In prediabetes, this system starts to break down. The main problem is a condition called insulin resistance. Your cells stop responding properly to insulin, so glucose builds up in your blood instead of entering the cells. Your pancreas tries to compensate by making more insulin, but over time it cannot keep up. Blood sugar levels rise gradually, landing in the gray zone between normal and diabetes.
The most important thing to know about prediabetes is that it is reversible. Unlike type 2 diabetes, which requires ongoing management, prediabetes is a window of opportunity. People who make specific lifestyle changes at this stage can bring their blood sugar back to the normal range and sharply lower their chances of ever developing diabetes.
How Common Is Prediabetes?
Prediabetes is far more common than most people realize. According to the latest figures from the U.S. Centers for Disease Control and Prevention, about 115.2 million American adults have prediabetes. That is more than 2 in every 5 adults, a figure that surprises even many health professionals.
What makes the problem worse is how few people know about it. Roughly 8 in 10 adults with prediabetes have no idea they have the condition. Because prediabetes usually causes no clear symptoms, it can go undetected for years. Many people only discover they had it after they have already crossed the line into type 2 diabetes, or after routine blood work finally flags the problem.
Rates are rising in younger adults too, driven by rising rates of excess weight and sedentary lifestyles. The condition is also more common among African American, Hispanic and Latino, American Indian, Alaska Native, Asian American, and Pacific Islander adults, who face a higher risk of both prediabetes and type 2 diabetes.
The scale of the problem matters because prediabetes is not harmless. Even before blood sugar reaches the diabetes range, higher-than-normal glucose levels increase the risk of heart disease and stroke. The earlier it is caught, the more can be done about it.
Warning Signs and Symptoms of Prediabetes
Most people with prediabetes have no symptoms at all. That is the single most dangerous thing about the condition. You can feel perfectly fine while your blood sugar quietly climbs for months or years. This is why doctors recommend blood sugar testing for people with risk factors, even when they feel healthy.
That said, some people do notice subtle signs as their blood sugar rises. Because these signs are easy to dismiss, it helps to know what they look like.
Common warning signs
- Increased thirst: Feeling thirstier than usual and drinking more water without an obvious reason.
- Frequent urination: Needing to use the bathroom more often, especially at night, as your kidneys work to flush out extra sugar.
- Unusual fatigue: Feeling tired even after a full night of sleep, because your cells are not getting glucose efficiently.
- Blurred vision: Temporary changes in eyesight caused by fluid shifts in the lenses of the eyes when blood sugar runs high.
- Slow-healing cuts or sores: Minor wounds taking longer than usual to heal.
- Tingling or numbness: A pins-and-needles feeling in the hands or feet, though this is more common as blood sugar rises further.
Acanthosis nigricans: a visible clue
One distinctive sign linked to insulin resistance is a skin change called acanthosis nigricans: dark, thick, velvety patches, most often on the back of the neck, in the armpits, or in the groin area. It is not dirt and does not wash off. If you notice this kind of darkening, mention it to your doctor.
The bottom line on symptoms is simple: do not wait for warning signs before getting tested. By the time symptoms are obvious, blood sugar is often already in the diabetes range. A simple blood test is the reliable way to know where you stand.
Prediabetes Test Ranges You Should Know
Three standard blood tests are used to diagnose prediabetes, and doctors may use one or more of them. Knowing the cutoff numbers helps you understand your own results.
1. Fasting plasma glucose test
This test measures your blood sugar after you have not eaten for at least eight hours, usually first thing in the morning.
- Normal: less than 100 mg/dL (5.6 mmol/L)
- Prediabetes: 100 to 125 mg/dL (5.6 to 6.9 mmol/L)
- Diabetes: 126 mg/dL (7.0 mmol/L) or higher
2. A1C test
The A1C test reflects your average blood sugar over the past two to three months. It does not require fasting, which makes it convenient, and it is the test most often used for routine screening.
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
3. Oral glucose tolerance test (OGTT)
For this test, you drink a sugary solution and your blood sugar is measured two hours later. It shows how well your body handles a glucose load.
- Normal: less than 140 mg/dL (7.8 mmol/L)
- Prediabetes: 140 to 199 mg/dL (7.8 to 11.0 mmol/L)
- Diabetes: 200 mg/dL (11.1 mmol/L) or higher
Doctors generally repeat an abnormal result on a different day before confirming a diagnosis, since blood sugar can vary. If your results fall in the prediabetes range, your doctor will usually recommend retesting once a year to watch for any movement toward diabetes.
Risk Factors for Prediabetes
Anyone can develop prediabetes, but certain factors raise your risk. Some you cannot change, and some you can. Knowing which category you fall into helps you focus your efforts.
- Excess weight: Carrying extra weight, especially around the waist, is the strongest risk factor, because belly fat makes cells more resistant to insulin.
- Age 45 or older: Risk rises with age, partly because people tend to exercise less and gain weight as they get older.
- Family history: Having a parent or sibling with type 2 diabetes raises your odds.
- Physical inactivity: Being active less than three times a week increases risk, because idle muscles use less glucose.
- History of gestational diabetes: Women who had diabetes during pregnancy face a much higher later risk.
- Giving birth to a large baby: Having had a baby weighing more than 9 pounds is linked to higher risk.
- Polycystic ovary syndrome (PCOS): Women with PCOS are more likely to develop insulin resistance.
- High blood pressure and unhealthy cholesterol: High triglycerides, low HDL cholesterol, and high blood pressure often travel together with prediabetes.
- Sleep problems: Consistently poor sleep or untreated sleep apnea is linked to insulin resistance.
- Smoking: Smoking increases insulin resistance and raises diabetes risk.
- Race and ethnicity: African American, Hispanic and Latino, American Indian, Alaska Native, Asian American, and Pacific Islander people face higher risk at lower body weights.
If you have several of these risk factors, ask your doctor about screening. Most guidelines recommend testing for adults starting at age 35, and earlier for people with extra risk factors.
Can Prediabetes Be Reversed?
Yes. In most cases, prediabetes can be reversed through lifestyle changes, without medication. The U.S. Diabetes Prevention Program, one of the largest prevention studies ever conducted, showed that lifestyle changes reduced the development of type 2 diabetes by 58% over three years, and by 71% in people aged 60 and older. The goal is a set of steady, sustainable changes, not a crash diet or extreme exercise plan.
Lose a modest amount of weight
The Diabetes Prevention Program found that losing just 5 to 7 percent of body weight made a major difference. For a person weighing 200 pounds, that is 10 to 14 pounds. Even modest weight loss reduces the fat around your organs and makes your cells respond to insulin more effectively.
Get regular physical activity
Aim for at least 150 minutes per week of moderate activity, such as brisk walking, cycling, or swimming, which breaks down to about 30 minutes on five days of the week. Exercise burns glucose directly and makes your muscles more sensitive to insulin for hours afterward. Add some resistance training two or three times a week, and break up long periods of sitting by standing or walking briefly every 30 minutes.
Eat for stable blood sugar
There is no single official “prediabetes diet,” but the eating pattern that works best is built on a few consistent principles:
- Fill half your plate with vegetables. Leafy greens, broccoli, peppers, and cauliflower add fiber and volume with very little effect on blood sugar.
- Choose whole grains over refined ones. Swap white bread, white rice, and sugary cereals for oats, brown rice, whole-wheat bread, and legumes. Fiber slows sugar absorption.
- Include lean protein and healthy fats. Beans, lentils, fish, poultry, eggs, nuts, and olive oil help you feel full and prevent blood sugar spikes.
- Cut back on sugary drinks. Soda, sweetened tea, energy drinks, and fruit juices deliver a large sugar load with no fullness. Choose water or unsweetened tea instead.
- Watch portions and added sugars. Regular, balanced meals help avoid the big blood sugar swings that come from skipping meals and then overeating.
Sleep well and manage stress
Poor sleep raises the stress hormone cortisol, which pushes blood sugar higher and worsens insulin resistance. Aim for seven to nine hours of sleep per night, and find regular ways to unwind, whether through walking, breathing exercises, or time with people you enjoy.
Consider a structured prevention program
The CDC recognizes diabetes prevention programs, including online and in-person options, that teach practical skills for eating, activity, and weight loss over the course of a year. Participants often do far better than people who try to change habits entirely on their own. In some cases, doctors also prescribe medication such as metformin for people at very high risk, as an add-on to healthy habits rather than a replacement for them.
When Does Prediabetes Become Type 2 Diabetes?
Prediabetes becomes type 2 diabetes when blood sugar crosses the diagnostic thresholds: a fasting glucose of 126 mg/dL or higher, an A1C of 6.5% or higher, or a two-hour glucose tolerance result of 200 mg/dL or higher.
Without intervention, this progression can happen faster than many people expect. Many people with prediabetes develop type 2 diabetes within five years if they make no changes. Once that line is crossed, the focus shifts from reversal to long-term management, because type 2 diabetes requires ongoing care and raises the risk of serious complications such as heart disease, kidney failure, vision loss, and nerve damage.
The reverse is also true: with consistent lifestyle changes, A1C levels can fall back into the normal range, and the diagnosis of prediabetes can effectively be reversed. Doctors usually monitor this with an A1C test every year.
The Bottom Line
Prediabetes is a serious warning, but it is also an opportunity. More than 2 in 5 American adults have it, most without knowing, and many will develop type 2 diabetes within a few years if nothing changes. Yet research shows that modest weight loss, 150 minutes of weekly activity, and steadier eating habits can cut that risk dramatically and even bring blood sugar back to normal.
This article is for general information only and is not medical advice. Blood sugar targets and treatment decisions are personal, so please talk to your doctor or another qualified health professional before making changes based on this information.
