📚 Part of our Blood Sugar Guide — an evidence-based guide.
Prediabetes is one of the few diagnoses that is genuinely good news to receive, because it names a problem at the stage when the outcome can still be changed. The evidence that it responds to ordinary behaviour is unusually strong — stronger, in the landmark trial, than the evidence for the medication used alongside it.
What prediabetes actually is
Prediabetes means blood sugar is higher than normal but not yet in the diabetes range. It is defined by any of:
- A1C of 5.7% to 6.4%
- Fasting glucose of 100 to 125 mg/dL
- Two-hour glucose of 140 to 199 mg/dL after an oral glucose tolerance test
It is extraordinarily common — roughly one in three American adults — and most people who have it do not know. Our own analysis of NHANES 2021–2023 found that among adults with an A1C in that range, 70.9% had never been told, about 41.7 million people (the full analysis).
Underneath it is insulin resistance, which has usually been developing for years before any test turns abnormal.
The evidence that it reverses
This is not motivational thinking. The Diabetes Prevention Program was a large randomised trial in the United States that assigned people with prediabetes to one of three arms: an intensive lifestyle programme, metformin, or placebo.
The lifestyle arm aimed at 7% weight loss and 150 minutes a week of moderate activity. It reduced progression to type 2 diabetes by roughly 58% over about three years. Metformin reduced it by around 31%. Lifestyle beat the drug, and by a wide margin.
Two details make that finding more useful than the headline. The benefit was greatest in older participants, where metformin worked least well. And follow-up over the following decades showed the reduction in diabetes incidence persisted long after the intensive programme ended — the effect did not simply evaporate.
What “reversal” means, honestly
Returning to a normal A1C is a real and common outcome. But it is worth being precise about what has and has not changed.
Your underlying tendency toward insulin resistance does not disappear. Genetics, age and the years of physiology that got you here are still there. What changes is that the demand on your pancreas falls enough for glucose to normalise. Regain the weight or stop moving, and the numbers typically come back.
The right mental model is not “cured” but “controlled, and the control has to continue” — much like blood pressure. That is not a discouraging framing. It simply sets the expectation correctly, which matters because people who expect permanence often stop and are surprised.
What actually works, in order
1. Modest weight loss, if you carry excess. The threshold is lower than most people assume: 5 to 7% of body weight. For someone at 200 lb, that is 10 to 14 lb. Visceral fat, which drives the problem, tends to come off preferentially and early (how it works).
2. 150 minutes a week of moderate activity — the DPP target, and it does not have to be the gym. Post-meal walking is disproportionately effective because it lands when glucose is peaking, and muscle pulls glucose from the blood without needing insulin (the trial, the mechanism).
3. Strength training twice a week. More muscle means more capacity to store glucose safely, and it protects muscle during weight loss (why muscle decides).
4. Change the shape of your carbohydrate. More fiber and protein, fewer refined and liquid carbohydrates. Sequencing helps measurably (meal order, what to cut).
5. Sleep. Short and irregular sleep reduce insulin sensitivity directly, and no dietary precision compensates (the connection).
Where metformin fits
Guidelines suggest considering metformin for prediabetes in specific higher-risk groups — broadly, people under 60, those with a BMI of 35 or above, women with a history of gestational diabetes, and those whose A1C stays high despite lifestyle change.
It is not a substitute for the behaviour change; in the trial it was less effective, particularly in older people. But for someone in those higher-risk categories it is a reasonable conversation to have rather than something to resist.
How to know whether it is working
Ask for a repeat A1C in about three months. That interval matches the biology of the test, since A1C reflects roughly the previous two to three months.
Do not judge by how you feel — prediabetes produces no symptoms, and neither does reversing it. Weight and waist are useful interim markers between blood tests, and waist often improves before the scale does (why the scale is noisy).
The honest limits
Not everyone fully reverses, and saying otherwise would be dishonest. Genetics matter substantially. Beta-cell function declines with age regardless of behaviour. Some people do everything correctly and progress anyway — more slowly, which is itself worth a great deal.
The earlier you act, the better the odds. And even where progression is not prevented, the same changes reduce cardiovascular risk, which is what actually kills most people with diabetes.
When to see a doctor
Get a fasting glucose and A1C if you have never had them, are 45 or older, carry excess weight around the middle, have a family history of type 2 diabetes, had gestational diabetes, have high blood pressure, or have PCOS. Certain ethnic backgrounds warrant earlier screening.
Go sooner for excessive thirst, frequent urination, unexplained weight loss, blurred vision or slow-healing wounds. And if you have already been told you have prediabetes, ask specifically about a referral to a recognised Diabetes Prevention Program — the structured version of the intervention that produced these results is available in many places and is often covered.
The honest bottom line
Prediabetes frequently reverses, and the evidence for that comes from a large randomised trial where lifestyle change outperformed metformin by a wide margin — a 58% reduction in progression, with the benefit persisting for decades. The targets are unremarkable: 5 to 7% weight loss and 150 minutes a week of movement. What reversal does not mean is cure — the tendency remains, and the changes have to continue. Retest at three months, and do not wait to feel something, because you will not.
Before acting on a borderline result, check what A1C really measures and when it is wrong.
Frequently asked questions
What blood sugar level is prediabetes?
Prediabetes is an A1C of 5.7% to 6.4%, or a fasting blood sugar of 100 to 125 mg/dL. Above those ranges is type 2 diabetes; below is normal.
Can prediabetes be reversed?
Yes, frequently. Landmark research shows that modest weight loss and regular activity can return blood sugar to normal for many people and sharply cut the risk of developing type 2 diabetes.
How long does it take to reverse prediabetes?
It varies, but many people see meaningful improvement within a few months of consistent lifestyle changes. A repeat A1C test after about 3 months shows progress.