Prediabetes is a precursor to type 2 diabetes, not type 1. It means your blood sugar is higher than normal but not yet high enough to qualify as type 2 diabetes. Without changes, prediabetes carries a high risk of progressing to full type 2 diabetes. Over 115 million American adults have prediabetes, and 8 in 10 of them don’t know it.
Why Prediabetes Is Linked to Type 2
Type 2 diabetes is driven by insulin resistance, a condition where your muscle, fat, and liver cells stop responding well to insulin. Insulin is the hormone that moves sugar from your blood into your cells for energy. When your cells resist that signal, your pancreas has to pump out more and more insulin to compensate. Over time, the pancreas can’t keep up, and blood sugar starts to rise.
Prediabetes is the early phase of this process. Your blood sugar is creeping up because insulin resistance has already taken hold, but your pancreas is still producing enough insulin to keep levels below the type 2 threshold. It’s the same underlying problem, just at an earlier point on the spectrum.
Type 1 Diabetes Works Differently
Type 1 diabetes has nothing to do with insulin resistance. It’s an autoimmune disease where the immune system mistakenly destroys the cells in the pancreas that produce insulin. Without those cells, the body can’t make insulin at all.
Type 1 does have its own early stages, but they aren’t called “prediabetes.” Doctors identify them by testing for autoantibodies, proteins that signal the immune system is attacking the pancreas. The staging works like this:
- Stage 1: Two or more autoantibodies are present, but blood sugar is still normal and there are no symptoms. People can stay at this stage for years.
- Stage 2: Autoantibodies are present and blood sugar has become abnormal, but symptoms still haven’t appeared.
- Stage 3: Blood sugar is high and symptoms like excessive thirst, frequent urination, and weight loss are present. This is the point most people associate with a type 1 diagnosis.
So while both types of diabetes have a buildup period before full diagnosis, only the type 2 version is called prediabetes. The early stages of type 1 are tracked through autoantibody screening, which is a completely different test.
How Prediabetes Is Diagnosed
Three blood tests can identify prediabetes, and any one of them is enough for a diagnosis:
- A1C test: Measures your average blood sugar over the past two to three months. Prediabetes falls in the range of 5.7% to 6.4%.
- Fasting blood sugar: Taken after an overnight fast. A result between 100 and 125 mg/dL indicates prediabetes.
- Oral glucose tolerance test: Measures blood sugar two hours after drinking a sugary solution. A reading between 140 and 199 mg/dL falls in the prediabetes range.
At or above the upper end of any of those ranges, the diagnosis shifts to type 2 diabetes.
Physical Signs to Watch For
Prediabetes typically has no obvious symptoms, which is why so many people don’t know they have it. But one visible clue is a skin condition called acanthosis nigricans: dark, thick, velvety patches of skin that usually appear on the back of the neck, in the armpits, or in the groin. These patches develop slowly and may feel itchy or have a slight odor. They’re a direct sign of insulin resistance, and people who have them are significantly more likely to develop type 2 diabetes.
Beyond that skin change, prediabetes is mostly silent. Risk factors include being overweight, being physically inactive, having a family history of type 2 diabetes, and being over age 45.
Prediabetes Can Be Reversed
This is the most important distinction between prediabetes and a type 2 diagnosis: prediabetes is highly reversible. The landmark Diabetes Prevention Program trial found that moderate lifestyle changes (losing a modest amount of weight through better eating and about 150 minutes of physical activity per week) reduced the risk of developing type 2 diabetes by 58%. That study was so effective it was ended early because the results were already clear after less than three years.
For comparison, a commonly used medication reduced risk by 31% in the same trial. Lifestyle changes were nearly twice as effective. The core changes aren’t dramatic. Losing 5% to 7% of your body weight (roughly 10 to 14 pounds for someone who weighs 200) and walking briskly for 30 minutes a day, five days a week, is enough to make a measurable difference in blood sugar levels and long-term risk.
Because prediabetes sits on the type 2 spectrum, it responds to the same interventions that prevent type 2: moving more, eating fewer refined carbohydrates, and maintaining a healthier weight. None of these strategies apply to type 1 diabetes, which can’t be prevented or reversed through lifestyle changes.