Lowering Blood Sugar Levels Can Cut Cardiovascular Risks

New research shows that reversing high blood sugar — even before diabetes develops — can dramatically improve heart health

Kristen Fischer,

AARP

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Published December 23, 2025

Stacks of sugar cubes gradually decrease in height against a blue background, illustrating falling blood sugar levels

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People with prediabetes who bring their blood sugar levels back to the normal range can reduce their risk of dying from heart disease or being hospitalized for heart failure by more than half, a new study finds.

Prediabetes, a condition where blood sugar levels are higher than normal but not yet in the diabetes range, is linked to heart attacks, heart disease and death. An estimated 98 million American adults, or more than 1 in 3, have prediabetes, according to the U.S. Centers for Disease Control and Prevention — and many more don’t know they have it.

Previous research largely showed that people with prediabetes can delay or prevent type 2 diabetes by controlling their blood sugar, or glucose, levels. But this latest report, published Dec. 12 in The Lancet Diabetes & Endocrinology, shows that if an individual with prediabetes is able to return their sugar levels to normal ranges — what’s known as prediabetes remission — they can have better cardiovascular outcomes.

“Prediabetes is not a ‘wait and see’ diagnosis,” says Dr. Andreas L. Birkenfeld, coauthor of the new study and director and chair of the Department of Diabetology, Endocrinology and Nephrology at Germany’s University Hospital Tübingen. “It’s a meaningful stage where you can still shift back toward metabolic health — and the earlier you normalize glucose, the better.”

A closer look at the study

The team used data from some of the largest studies across the U.S. and China, involving 2,942 participants who had prediabetes. In the U.S. trial, participants completed a one-year intervention combining exercise with either metformin or a placebo, while the Chinese trial involved a six-year program focusing on diet, exercise or both.

When researchers reviewed the data 20 years after the U.S. intervention and 30 years after the intervention in China, they found that participants who normalized their glucose levels had about a 50 percent lower risk of dying from cardiovascular disease or being hospitalized for heart failure.Maintaining a fasting blood glucose value of 97 milligrams per deciliter or less was enough to lower the risk for heart disease regardless of weight, age or ethnicity, the researchers found. (For reference, 70 to 99 mg/dL is considered normal in those without diabetes, though some normal references go down to 50 mg/dL, the Cleveland Clinic says.)

How high blood sugar can affect the cardiovascular system

High glucose can directly harm your blood vessels by preventing the vessel lining from properly dilating, which increases inflammation and promotes plaque buildup. That’s an early step toward atherosclerosis, or the hardening of the arteries, Birkenfeld says.

Too much glucose can also damage small vessels and can contribute to heart failure, says Elizabeth Selvin, a clinical research professor and diabetes researcher at the Johns Hopkins Bloomberg School of Public Health.

“This process is cumulative and happens over a long period of time, which is why keeping glucose in the normal range and preventing diabetes is so important,” Selvin says.

Another reason to keep blood sugar in check: It can improve key drivers of cardiometabolic health. Lower glucose levels help reduce insulin resistance, cut visceral fat (the deep fat around your organs), decrease liver fat and boost insulin secretion and cell function, Birkenfeld says. These changes likely ease inflammation and reduce stress on blood vessels as glucose returns to normal, he adds.

Is it too late to start lowering your glucose levels?

While the study didn’t pinpoint the best time to start lowering blood sugar for maximum heart benefits, experts say don’t wait to take action.

“If your doctor is telling you that ‘I’m worried about your blood sugar — you’re not diabetic yet but you could be,’ that’s a really crucial time to focus on things that we know work to prevent your future risk of diabetes and reduce your future risk of heart disease,” says Dr. Jonathan Newman. He is an associate professor of medicine at the NYU Grossman School of Medicine and clinical research director at NYU Langone’s Center for the Prevention of Cardiovascular Disease.

However, the research does show that early intervention against prediabetes can have long-term downstream effects, Selvin says. That is, intensive intervention that results in weight loss and lower glucose levels for several years appears to have long-term benefits, even if people bounce back to their normal weight after the intervention period is over — a phenomenon known as the legacy effect, she explains.

“The message is that remission may protect you from heart attack, heart failure and premature death — and that’s a powerful motivation to act,” Birkenfeld says.

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Kristen Fischer is a contributing writer at AARP based at the Jersey Shore. She has also written for Health, WebMD, and McKnights and is the author of Zoo Zen: A Yoga Story for Kids.