Prediabetes is a condition where your blood sugar is higher than normal but not yet high enough to qualify as type 2 diabetes. It affects more than 115 million American adults, over 2 in 5, and 8 in 10 of them don’t know they have it. That’s largely because prediabetes rarely causes obvious symptoms, making blood tests the only reliable way to catch it.
The good news: prediabetes is reversible. Modest changes in weight and activity can cut your risk of progressing to type 2 diabetes by more than half.
How Blood Sugar Levels Define Prediabetes
Three blood tests can identify prediabetes, each measuring blood sugar in a different way. Your doctor may use one or more of them.
- A1C test: Reflects your average blood sugar over the past two to three months. A result of 5.7% to 6.4% falls in the prediabetes range. Below 5.7% is normal, and 6.5% or higher indicates diabetes.
- Fasting blood sugar: Taken after at least eight hours without eating. A reading of 100 to 125 mg/dL signals prediabetes. Normal is below 100, and 126 or above points to diabetes.
- Oral glucose tolerance test: Measures blood sugar two hours after drinking a sugary solution. A result between 140 and 199 mg/dL indicates prediabetes.
These ranges exist on a spectrum. Someone at 6.3% on the A1C is at significantly higher risk of progressing to diabetes than someone at 5.8%, even though both technically have prediabetes.
What’s Happening Inside Your Body
Prediabetes involves two related problems: your cells become less responsive to insulin, and the insulin-producing cells in your pancreas start to struggle.
Insulin is the hormone that moves sugar from your blood into your cells for energy. When your muscle, fat, and liver cells stop responding to insulin efficiently, a condition called insulin resistance, your pancreas compensates by producing more of it. For a while, that extra insulin keeps blood sugar in check. But over time, the pancreas can’t keep up with the increased demand. The insulin-producing cells begin to wear down, releasing less insulin or releasing it too slowly after meals. Blood sugar starts creeping upward.
Research suggests that this decline in insulin-producing cell function is actually the more critical factor in the progression toward diabetes. Insulin resistance sets the stage, but it’s the failure of those pancreatic cells to compensate that tips the balance. Many of the genetic risk variants linked to type 2 diabetes act specifically by impairing insulin secretion rather than insulin sensitivity, which means some people are predisposed to this breakdown from the start.
Signs You Might Notice
Most people with prediabetes feel perfectly fine, which is why the condition goes undetected so often. There are no classic symptoms like frequent urination or extreme thirst at this stage.
One visible clue that sometimes appears is a skin change called acanthosis nigricans: patches of darkened, velvety skin that typically show up in skin folds like the neck, armpits, or groin. These patches develop because excess insulin in the blood stimulates skin cell growth. Skin tags in the same areas can also be associated with insulin resistance. Neither of these is a definitive sign of prediabetes, but if you notice them, it’s worth getting your blood sugar checked.
Who’s Most at Risk
Several factors increase your likelihood of developing prediabetes. Some you can influence, others you can’t.
Weight is the strongest modifiable risk factor. Research identifies a BMI around 28 to 30 as the threshold where prediabetes risk rises meaningfully, though this varies by sex. For men, a BMI above roughly 29.6 and a waist circumference above about 90 cm (35.4 inches) were the most predictive cutoffs in population studies. For women, a BMI above 28.3 and a waist above 88 cm (34.6 inches) carried elevated risk. Waist circumference matters because fat stored around the abdomen is more metabolically active and contributes more directly to insulin resistance than fat stored elsewhere.
Beyond weight, the major risk factors include being over 45, having a parent or sibling with type 2 diabetes, being physically inactive, having had gestational diabetes during pregnancy, and belonging to certain racial and ethnic groups including Black, Hispanic, Native American, Asian American, and Pacific Islander populations. Polycystic ovary syndrome and a history of cardiovascular disease also increase risk.
Health Risks Beyond Diabetes
Prediabetes isn’t just a warning sign for future diabetes. It carries its own health consequences, even if it never progresses further. A large study tracking long-term outcomes found that people with prediabetes had a 38% higher risk of atherosclerotic cardiovascular disease, which includes heart attacks and strokes, compared to people with normal blood sugar. Their risk of chronic kidney disease was 25% higher.
What’s striking is that these elevated risks persisted even after researchers accounted for whether someone eventually developed diabetes. In other words, prediabetes itself, not just the diabetes it may lead to, appears to damage blood vessels and organs over time. The years spent with mildly elevated blood sugar take a toll on the cardiovascular system.
How to Reverse Prediabetes
The landmark Diabetes Prevention Program trial, published in the New England Journal of Medicine, is the strongest evidence that prediabetes can be reversed. The study assigned over 3,200 people with prediabetes to either a lifestyle intervention, medication, or a placebo. The lifestyle group aimed for two specific targets: losing at least 7% of their body weight and getting at least 150 minutes of moderate physical activity per week, roughly 30 minutes of brisk walking five days a week.
The results were dramatic. The lifestyle intervention reduced the rate of progression to type 2 diabetes by 58% compared to the placebo group. For someone weighing 200 pounds, the weight loss goal translates to about 14 pounds. Participants didn’t need to follow extreme diets or intense exercise programs. They ate a lower-calorie, lower-fat diet and walked regularly.
Medication was also effective but less so. Participants taking a common blood-sugar-lowering drug reduced their risk by 31%. Guidelines generally reserve medication for higher-risk individuals, specifically those who have both elevated fasting blood sugar and impaired glucose tolerance along with at least one additional risk factor such as a BMI of 35 or higher, a family history of diabetes, elevated triglycerides, low HDL cholesterol, or an A1C above 6.0%.
For most people with prediabetes, lifestyle changes alone are the first and most effective approach. The changes don’t need to be all-or-nothing. Even losing 5% of your body weight produces measurable improvements in insulin sensitivity. Small, sustained shifts in eating and activity patterns compound over time, and the pancreatic cells that produce insulin can recover function when the metabolic burden on them is reduced.