Prediabetes means your blood sugar is higher than normal but not yet high enough to be classified as type 2 diabetes. It’s a warning stage, not a diagnosis of diabetes, and it’s remarkably common: over 115 million American adults have it, and 8 in 10 of them don’t know. Without changes, many people with prediabetes develop type 2 diabetes within five years. The good news is that prediabetes is reversible.
What’s Happening in Your Body
To understand prediabetes, it helps to know how your body normally handles sugar. When you eat, your digestive system breaks carbohydrates down into glucose, which enters your bloodstream. Your pancreas then releases insulin, a hormone that acts like a key, unlocking your cells so they can absorb that glucose and use it for energy.
In prediabetes, your cells start resisting insulin’s signal. Skeletal muscle is the biggest reservoir for blood sugar, absorbing up to 70% of circulating glucose, so when muscle tissue stops responding well to insulin, glucose builds up in your blood. Your pancreas compensates by pumping out more insulin, and for a while this extra effort keeps your blood sugar in a near-normal range. But over time the pancreas can’t keep up with the increasing demand. That’s when blood sugar levels creep into the prediabetic range, and eventually, if nothing changes, into the diabetic range.
How Prediabetes Is Diagnosed
There are three blood tests used to identify prediabetes, and any one of them is sufficient for a diagnosis.
- A1C test: This measures your average blood sugar over the past two to three months. A result between 5.7% and 6.4% indicates prediabetes. It doesn’t require fasting, which makes it the most convenient option.
- Fasting plasma glucose: You fast overnight, then have your blood drawn. A fasting level between 100 and 125 mg/dL falls in the prediabetic range.
- Oral glucose tolerance test: After fasting, you drink a sugary solution and have your blood drawn two hours later. A reading between 140 and 199 mg/dL at that two-hour mark signals prediabetes.
Your doctor may use one or a combination of these, depending on the situation. Results can vary slightly between tests, so a borderline result on one may be confirmed or ruled out by another.
Symptoms Are Rare, but Not Nonexistent
Prediabetes typically produces no noticeable symptoms, which is why so many people have it without knowing. You can feel perfectly healthy while your blood sugar is quietly climbing. This is also why routine screening matters, especially if you have risk factors.
One possible visible sign is darkened, velvety patches of skin on the neck, armpits, or groin. This skin change, called acanthosis nigricans, is linked to insulin resistance. It’s not dangerous on its own, but if you notice it, it’s worth mentioning to your doctor as a reason to check your blood sugar.
Who’s at Higher Risk
Several factors increase your chances of developing prediabetes. Carrying extra weight, particularly around the midsection, is one of the strongest predictors. Physical inactivity, a family history of type 2 diabetes, and age (risk rises after 35) all play roles. A history of gestational diabetes also raises long-term risk.
Race and ethnicity matter statistically. Asian, Black, and Hispanic adults all have a higher prevalence of prediabetes than white adults. Researchers emphasize that these differences reflect social and environmental factors, such as access to healthy food and healthcare, rather than inherent biological differences.
Why Prediabetes Isn’t “Just” a Warning
It’s tempting to view prediabetes as a harmless precursor, something that only becomes a problem if it progresses to full diabetes. That’s not quite right. Even at the prediabetic stage, elevated blood sugar can begin affecting your body in meaningful ways.
A study published in the Journal of Clinical Endocrinology and Metabolism found that people with prediabetes had a 38% higher risk of cardiovascular events like heart attack and stroke compared to those with normal blood sugar. The same study found a 23% higher risk of worsening protein leakage in the kidneys, an early marker of kidney damage. The mechanisms behind this include damage to blood vessel linings, increased inflammation, and changes in how the heart uses fuel. In other words, the damage associated with diabetes doesn’t wait for diabetes to officially arrive.
Lifestyle Changes That Reverse It
The strongest evidence for reversing prediabetes comes from the Diabetes Prevention Program, a major clinical trial that has shaped national guidelines. Participants who lost 5% to 7% of their body weight (that’s 10 to 14 pounds for someone weighing 200 pounds) and exercised at least 150 minutes per week reduced their risk of developing type 2 diabetes by 58%. That’s a larger effect than any medication tested in the same trial.
The 150-minute weekly target breaks down to about 30 minutes of moderate activity five days a week. Brisk walking counts. You don’t need a gym membership or an intense training program. The weight loss component focused on reducing calories, not following any specific diet trend. What mattered was the overall reduction in body weight, not the method used to get there.
These aren’t theoretical recommendations. The CDC built a nationwide program called the National Diabetes Prevention Program based on these results, offered through YMCAs, community health centers, and online platforms. The program typically runs for a year and provides group coaching to help people make and sustain these changes.
When Medication Enters the Picture
For some people, lifestyle changes alone may not be enough, or the risk of progression may be high enough that a doctor recommends medication alongside those changes. The American Diabetes Association’s most current guidelines suggest considering metformin for adults at particularly high risk, specifically those under 60 with a BMI of 35 or above, a fasting glucose of 110 mg/dL or higher, an A1C of 6.0% or above, or a history of gestational diabetes.
Metformin works by reducing the amount of glucose your liver releases into your bloodstream and by improving your cells’ sensitivity to insulin. It’s been used for decades, is inexpensive, and is generally well tolerated. But it’s not a substitute for lifestyle changes. In the Diabetes Prevention Program trial, lifestyle modification outperformed metformin across every age group and weight category.
What to Expect After a Diagnosis
If your blood work comes back in the prediabetic range, your doctor will likely recommend retesting every one to three years, depending on your numbers and risk factors. In the meantime, you’ll be encouraged to focus on the lifestyle changes described above. Some people bring their A1C back below 5.7% within a year. Others take longer, and some stabilize in the prediabetic range without progressing, which is still a win.
The key thing to understand about prediabetes is that it’s not a one-way street. Your blood sugar got here gradually, and it can come back down gradually too. The earlier you catch it, the easier that reversal tends to be.