Nearly 40 percent of U.S. adults—and 50 percent of those over 65—have prediabetes. Eight out of 10 don’t know it. On the upside, the toolbox for preventing or reversing prediabetes is expanding. Here’s what to know.

1. Prediabetes isn’t pre-disease.

“Don’t let the ‘pre’ fool you,” says the Centers for Disease Control and Prevention. “Prediabetes puts you at increased risk of developing type 2 diabetes, heart disease, and stroke.”

The good news: If you have pre­diabetes, losing excess weight and boosting exercise can help keep type 2 diabetes at bay. That was one takeaway from the Diabetes Prevention Program (DPP), a trial involving 3,234 people with prediabetes.

“The lifestyle intervention reduced the risk of type 2 diabetes by 58 percent,” says Dana Dabelea, professor of epidemiology and pediatrics at the University of Colorado.

And keeping your blood sugar under control may protect your blood vessels even if you never get diabetes.

“After the trial ended, everyone in the DPP was offered the lifestyle intervention,” explains Dabelea.

Over the next 15 years, the participants who kept a lid on their blood sugar did better.

“People who did not develop diabetes had nearly a 30 percent lower prevalence of damage in small blood vessels compared to those who developed diabetes,” notes Dabelea. That damage occurs mostly in the eyes, nerves, and kidneys.

And even among people who stayed in the prediabetes range, the lower their hemoglobin A1c, the lower their risk of damage to tiny blood vessels in the eyes.

“The higher the A1c, the higher the risk, even before you get to diabetes,” says Dabelea.

How does insulin resistance lead to prediabetes and type 2 diabetes?

Insulin acts as a key that allows blood sugar (glucose) to enter the body’s cells, where it is either burned for fuel or stored. But in some people, the key can’t open the lock. To compensate for that “insulin resistance,” the pancreas pumps out more and more insulin, but it’s not enough to keep blood sugar from creeping up to “prediabetes” levels. After years of straining to keep up, the pancreas starts to fail and blood sugar reaches the “diabetes” range.

(That’s type 2 diabetes. In type 1 diabetes, the body’s immune system destroys the pancreas’s ability to make insulin. Type 1 accounts for about 5 percent of diabetes.)

Scroll down to see if you’re at risk for type 2 diabetes.

2. Cut the crappy carbs.

“A stunning 40 percent of what we eat is added sugars and refined carbs,” says Christopher Gardner, professor of medicine at the Stanford University School of Medicine.

“Most people don’t do a good job of getting rid of those crappy carbs.”

Many diets—from Mediterranean to keto to Paleo—do get that job done, he points out.

“Looking across all the popular diets, you see no added sugar, no refined grain, lots of vegetables, and whole—rather than ultra-processed—foods,” says Gardner.

In a recent trial, he randomly assigned 33 people with prediabetes or type 2 diabetes to eat a keto (very-low-carb) or Mediterranean diet for 12 weeks each. Both diets were low in added sugars and refined grains and rich in non-starchy vegetables.

A key difference: People could eat fruits, beans, and whole, unprocessed grains on the Mediterranean diet, but not on the keto diet.

The main results: “Hemoglobin A1c fell on both diets,” says Gardner.

“LDL—so-called bad cholesterol—was worse for keto, but triglycerides were better.” And people lost about 15 pounds on each diet.

“If it’s a wash, why get rid of the beans, fruits, and grains?” asks Gardner. “They provide far more variety, so the Mediterranean diet is more appealing and easier to stick with.”

3. Think twice about a continuous glucose monitor.

“Meet your metabolism.” “See how your body responds to food in real time,” says Signos.com.

Levels, Lingo, Nutrisense, Signos, Stelo. They’re just some of the websites that sell continuous glucose monitors (CGMs). Since early 2024, when the FDA cleared the first device that didn’t need a prescription, the market for CGMs has exploded.

They’re not cheap. Most charge roughly $200 to $500 per month, depending on whether you sign up for 1, 3, 6, or 12 months.

The CGMs are all made by one of two companies: Abbott or Dexcom. And CGMs sold directly by those companies are cheaper. Abbott’s Hellolingo.com offers a 2-week CGM for just $49, and Dexcom’s Stelo.com sells a 1-month subscription for $89.

For people with type 1—and some with type 2—diabetes, a CGM that sends alerts for low blood sugar can replace frequent finger sticks to test blood sugar levels. Is a CGM worth the cost for everyone else? Here’s what to keep in mind:

Are CGMs accurate?

CGMs measure glucose levels in the space between cells just under your skin. The devices can detect the wide swings in blood sugar that occur in people with diabetes. But for smaller swings, their results may be less reliable.

“We often found different glucose responses to the same meals when people without diabetes simultaneously wore two different CGMs,” says Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases.

And you can’t jump to conclusions about foods based on one CGM reading, adds Hall.

“Our CGM responses to a meal on one day didn’t reliably predict the CGM response of the same person to the same meal on another day.”

Will CGMs help you lose weight?

“As glucose rises, so does insulin,” explains Lingo. “And when insulin is chronically elevated, it can impair the body’s ability to burn fat for energy. That’s why having steady glucose levels can help with losing and maintaining weight.”

But there’s no good evidence that lower—or “steady”—glucose levels cause people to lose weight.

“When we put people on a low-carbohydrate diet, they had much lower glucose levels on CGMs after meals than when they ate a high-carbohydrate diet,” says Hall. “But they didn’t lose more body fat on the low-carbohydrate diet.”

Likewise, CGM results didn’t track with weight loss in Gardner’s study.

“When people were on the Keto diet, the CGM data showed lower average blood sugar levels than when they were on the Mediterranean diet, but we saw no difference in overall weight loss,” he points out.

It’s not as though the calories in protein and fat don’t count. Ditto for the calories in fructose, even though it raises blood sugar far less than glucose.

“The CGM is a shiny new toy, and it has led some people to do whatever they can to blunt a normal glucose response, as if any kind of spike is unhealthy,” notes Gardner.

“But a spike doesn’t mean you’re going to gain weight. If you eat some carbs, it’s normal for your glucose to go up. Your body secretes insulin, and you put the glucose away.”

Don’t be alarmed by high glucose readings.

When researchers had 1,175 people aged roughly 50 to 70 wear a CGM for a week, those without diabetes or prediabetes spent three hours a day with their blood sugar above what many experts—and many CGMs—consider a healthy range (70 to 140 milligrams per deciliter).

(People with prediabetes spent 5½ hours—and those with diabetes averaged 13¾ hours—above that range.)

“Don’t panic,” says Nicole Spartano, assistant professor of medicine at the Boston University Chobanian & Avedisian School of Medicine, who led the study.

“We don’t yet know what CGM levels are of concern for people without diabetes or prediabetes.”

A CGM might get you moving.

“You can take a bite out of a glucose spike by doing 15 minutes of exercise 30 minutes after your meal,” says Spartano, citing a study on older people with prediabetes and obesity.

“Seeing that change on a CGM might increase your physical activity. But that may only last a few weeks, as we see with wearables like a Fitbit.”.

4. Exercise can reverse prediabetes.

Exercise can curb your risk of type 2 diabetes. Researchers are trying to figure out how...and which kind of exercise is best.

“We wanted to tease out whether high- and moderate-intensity exercise had similar benefits,” says Steven Malin, director of the Applied Metabolism & Physiology Laboratory at Rutgers University.

His team randomly assigned 31 sedentary older adults with prediabetes and obesity to one of two groups that did an hour of cycling every day for two weeks.

“Both groups burned the same 350 calories at each workout,” explains Malin. “But the continuous moderate-intensity exercise group cycled at about 70 percent of their maximum heart rate for an hour, while the high-intensity interval group alternated between 3 minutes at 90 percent of their maximum and 3 minutes at 50 percent for an hour.”

The results: “About 40 percent of both groups reversed their prediabetes,” says Malin. “That was pretty impressive for a two-week trial.”

(Of course, their prediabetes could have returned after the trial, especially if they stopped the exercise.)

What did the exercise change? When both groups took a glucose tolerance test—that is, when they drank a hefty dose of glucose—their blood sugar levels didn’t rise as much as it did when they entered the study. And their muscle cells were less insulin-resistant than when the study started.

What’s more, exercise revved up the insulin-secreting cells in the pancreas. “Beta-cell function improved similarly in the two groups,” notes Malin.

His bottom line: “Get out there and move. An hour a day should help your body produce insulin and help manage your blood glucose levels. It can be high-intensity interval exercise, but walking or biking is okay, too.”

5. Obesity meds work...and more are coming.

In a recent trial on people with prediabetes and obesity, 81 percent of semaglutide takers—but only 14 percent of placebo takers—no longer had prediabetes after one year.

(The trial was funded by Novo Nordisk, which sells semaglutide as Ozempic for diabetes and Wegovy for obesity.)

Remarkable? Yes. Surprising? No, since the drug is approved to treat not just obesity but—given its ability to lower blood sugar—type 2 diabetes.

(The same goes for tirzepatide, which is sold as Mounjaro for diabetes and Zepbound for obesity.)

How do the drugs reverse prediabetes?

“They’re improving insulin secretion from the beta-cells,” explained Ania Jastreboff, associate professor of medicine at the Yale School of Medicine, in Yale’s recent “Health
& Veritas” podcast.

And “if you lose weight, you’re improving insulin sensitivity,” she added, “because you’re offloading the work that the beta-cell has to do.”

(Jastreboff has led several clinical trials on tirzepatide and retatrutide funded by Eli Lilly and has served on the Scientific Advisory Boards for Eli Lilly, Novo Nordisk, Pfizer, Amgen, and several other companies.)

How do the drugs trigger weight loss?

Semaglutide is a long-acting version of a hormone released by the intestine—GLP-1 (glucagon-like peptide-1)—that slows gastric emptying and makes you feel full. Tirzepatide leads to even more weight loss because it’s a long-acting version of GLP-1 plus GIP (glucose-dependent insulinotropic polypeptide), which has similar effects.

But “this is just the tip of the iceberg,” Jastreboff noted. Among the dozens of meds in the pipeline:

• Survodutide. Long-acting GLP-1 plus glucagon, a hormone that curbs food intake.
• Retatrutide. Long-acting GLP-1 plus GIP and glucagon.
• CagriSema. A long-acting version of GLP-1 plus amylin, a hormone that slows stomach emptying.

The drugs are “all based on these hormones that are stimulated when we eat,” explained Jastreboff.

Also in the works: drugs to curb the loss of muscle and lean tissue that occurs whether you lose weight with drugs, surgery, or diet.

Drugs that extend the life of GLP-1 “have been around for over 20 years,” Jastreboff noted. But when it comes to the newer drugs’ safety, “we have to do our due diligence.” Stay tuned.

The bottom line

• The best way to dodge pre-diabetes or type 2 diabetes is to lose (or not gain) extra pounds. Cutting carbs—especially white flour, added sugars, and juices—may help lower blood sugar even if you don’t lose weight.
• Replace unhealthy carbs with unsaturated fats like olive or canola oil, nuts, and fish. Fill half your plate with nonstarchy vegetables.
• Aim for 30 to 60 minutes of brisk walking or other aerobic exercise daily.
• If you have prediabetes, find a CDC-recognized in-person or online Diabetes Prevention Program.
• If you have obesity, ask your physician about Ozempic-like medications. (So far, the drugs have been approved for treating type 2 diabetes but not prediabetes.)

Are you at risk for type 2 diabetes?

Want to estimate your risk of type 2 diabetes or prediabetes? Take this 60-second risk test from the American Diabetes Association.