High blood sugar: prediabetes, type 2 diabetes, and how nutrition brings it down

What causes high blood sugar?

After you eat, insulin moves sugar (glucose) out of the blood and into your cells. With insulin resistance, the body has to make more and more insulin to do the same job. Blood sugar creeps up, first into the prediabetes range, then, if the pancreas can’t keep up, into type 2 diabetes. The main drivers are excess fat in the abdomen and liver, inactivity, poor sleep and genetics. It’s the same insulin resistance that drives fatty liver, which is why the two so often appear together.

About 1 in 3 American adults has prediabetes, and roughly 8 in 10 of them don’t know it.

This page covers prediabetes and type 2 diabetes. Type 1 diabetes is an autoimmune condition with different care.

What your numbers mean

Ranges from the American Diabetes Association. A diabetes diagnosis needs confirmation by your doctor, usually with a repeat test.

Prevention and remission are real

In the Diabetes Prevention Program, people with prediabetes who lost about 7% of their body weight and did 150 minutes of activity a week were 58% less likely to develop type 2 diabetes than those who received standard advice, a bigger effect than the drug metformin.

For people who already have type 2 diabetes, remission is possible. It is defined as an A1C below 6.5% at least three months after stopping all glucose-lowering medication. It isn’t a cure: blood sugar can rise again, so it still needs checking regularly.

• The amount of weight lost is what matters most. A 2025 analysis of 22 randomized trials found that each 1% of body weight lost raised the chance of remission by about 2–3 percentage points. At one year, about 5% of people who lost less than 10% of their weight were in remission, about half of those who lost 10–19%, and about 7 in 10 of those who lost 20–29%.
• The landmark trial, DiRECT, used a medically supervised low-calorie formula diet followed by food reintroduction and ongoing support, in people diagnosed within the previous six years. 46% were in remission at one year and 36% at two years. By five years, about 1 in 10 were still in remission (versus 1 in 20 in the comparison group), and those who stayed in remission had kept more weight off.
• In the real world, England’s NHS remission program reported remission in roughly 3 in 10 people who completed it and had follow-up blood tests.

The takeaway: meaningful weight loss can put type 2 diabetes into remission, and keeping that weight off is what keeps it there. Most trials enrolled people within the first several years of their diagnosis.

How to lower blood sugar with nutrition

1. Lose abdominal and liver fat

Weight loss, especially from the abdomen and liver, is the most powerful lever for insulin resistance. A moderate, sustainable calorie deficit with plenty of protein protects muscle, which is itself a major place the body stores glucose. See weight loss that lasts.

2. Improve carbohydrate quality (and watch the amount)

Higher fiber intake is linked to a lower risk of type 2 diabetes, heart disease and early death. Build carbs around vegetables, legumes, whole grains and whole fruit; cut back on sugary drinks, juice, sweets and refined starches first. Reducing total carbohydrate has the most evidence for lowering blood sugar, but several eating patterns work. The right one is the one you can sustain.

3. Build every meal around protein and vegetables

Pairing carbohydrate with protein, fiber and some fat slows how fast sugar enters the blood. Eating the vegetables and protein on your plate before the starch can lower the after-meal spike further.

4. Move after you eat

Working muscles take up glucose without needing as much insulin. Even a few minutes of light walking after meals blunts the rise in blood sugar, and regular resistance training improves insulin sensitivity over time.

5. Sleep and timing

Short or poor sleep worsens insulin resistance. Some people also see better readings with a larger breakfast and lighter dinner. See Is it Bad to Skip Breakfast?

If you take insulin or a sulfonylurea (such as glipizide or glyburide), eating less or losing weight can push blood sugar too low. Talk with your doctor before changing your diet so your medication can be adjusted, and never stop a diabetes medication on your own. If you take an SGLT2 inhibitor (such as empagliflozin, dapagliflozin or canagliflozin), very-low-carbohydrate or very-low-calorie diets raise the risk of ketoacidosis, so check with your doctor first.