Overweight adults in the U.S. should now be screened for diabetes and prediabetes starting at age 35, a federal medical panel recommended Tuesday, saying that getting tested at an earlier age could help people avoid serious health complications later on.

The U.S. Preventive Services Task Force, an independent group of medical experts whose recommendations usually lead to insurance coverage of certain preventive services and tests, had previously recommended screening begin at age 40. The last update to its diabetes recommendations was in 2015.

The change in the screening recommendations comes partly from research showing that diabetes incidence increases at 35 years of age compared with younger ages, the panel said. It also took into consideration research showing that earlier medical treatment for newly diagnosed diabetes could be helpful in lowering the risk of heart attack and premature death.

The panel said it also looked at studies showing that lifestyle interventions, such as improving diet and increasing physical activity, reduced the progression of prediabetes to diabetes.

An estimated 13% of all U.S. adults have diabetes, while 34.5% have prediabetes, where blood sugar levels are higher than normal but not enough for a diabetes diagnosis, according to a 2020 report issued by the Centers for Disease Control and Prevention. Diabetes can lead to serious health complications, including heart disease, liver damage, blindness and kidney failure. People with diabetes are also at greater risk of becoming seriously ill if they get Covid-19.

Being overweight or obese is the strongest risk factor for developing prediabetes and full-blown diabetes, the panel said. People with a body-mass index of 25 or higher are considered overweight, while those who have a BMI of 30 or higher are considered obese, according to the CDC. Other risk factors include a family history of diabetes and older age.

“We know that you’re at a much higher risk of developing diabetes with age, but younger and younger people are developing the disease,” said Marie McDonnell, an endocrinologist and the director of the clinical diabetes program at Brigham and Women’s Hospital in Boston, who wasn’t a part of the federal panel. “If you can identify people at risk at younger ages, you can reduce the time that an individual spends in a diabetes-range blood sugar if you act on it.”

In the 2020 CDC report, researchers found that around 21% of those with diabetes weren’t aware or didn’t report that they had it, and only 15% of those with prediabetes said they were told by a healthcare professional that they had the condition.

Screening for diabetes involves a blood test, sometimes done after fasting, or, less commonly, a glucose tolerance test, which takes around three hours and involves the patient ingesting a syrupy drink to test the body’s response to sugar.

Write to Sarah Toy at sarah.toy@wsj.com