Prediabetes— where blood sugar levels are high, but not high enough for a diagnosis of type 2 diabetes—is not something you should dismiss.

It significantly increases the risk of heart attack, stroke and other serious heart problems, new research shows.

The findings highlight the need for health care providers and patients to prevent prediabetes, according to authors of the study scheduled for presentation May 16 at a virtual meeting of the American College of Cardiology.

"In general, we tend to treat prediabetes as no big deal. But we found that prediabetes itself can significantly boost someone's chance of having a major cardiovascular event, even if they never progress to having diabetes," lead author Dr. Adrian Michel said in a meeting news release.

"Instead of preventing diabetes, we need to shift focus and prevent prediabetes," said Michel, a resident at Beaumont Hospital-Royal Oak in Michigan.

Type 2 diabetes is a leading risk factor for heart attack, stroke and blockages in the heart's arteries. The heart risk posed by prediabetes has been less clear, so Michel and his colleagues analyzed data from nearly 25,000 patients treated by the Beaumont Health System between 2006 and 2020.

Over an average five-year follow-up, serious heart events occurred in 18% of patients with prediabetes compared with 11% of those with normal blood sugar levels.

The link between prediabetes and heart events remained significant even after the researchers accounted for other factors that could play a role, including age, gender, body fat, blood pressure, cholesterol, sleep apnea, tobacco use and peripheral artery disease.

"Based on our data, having prediabetes nearly doubled the chance of a major adverse cardiovascular event, which accounts for 1 out of 4 deaths in the U.S.," Michel said.

He said it's important for clinicians to educate patients about the heart-related risks associated with elevated blood sugar levels and to consider starting medication much earlier or more aggressively. Patients also need to be told about ways to reduce their risk, including exercise and a healthy diet, Michel said.

The study found that even when patients with prediabetes got their blood sugar level back to normal, they still had a higher risk of a heart event than those without prediabetes or diabetes.

"Even if blood sugar levels went back to normal range, it didn't really change their higher risk of having an event, so preventing prediabetes from the start may be the best approach," Michel said.

About 34 million Americans—just over 1 in 10—have diabetes and another 88 million—about 1 in 3—have prediabetes, according to the U.S. Centers for Disease Control and Prevention.

Research presented at meetings is typically considered preliminary until published in a peer-reviewed journal.