Loneliness is worse than a bad diet, smoking, or depression for people with diabetes, according to a new study

• A new study suggests loneliness could increase heart disease risk in patients with diabetes.
• The authors found loneliness is a bigger risk factor than diet, smoking, exercise, or depression.

Loneliness isn't a pleasant feeling for anyone — but for patients with diabetes, that feeling could be deadly.

Researchers at Tulane found that loneliness may be a bigger risk factor for heart disease in diabetes patients than a bad diet, smoking, lack of exercise, or depression.

Their study, published in the European Heart Journal on Thursday, followed more than 18,500 UK adults with diabetes aged 37 to 73. None of the subjects had heart disease.

In the following decade, about 3,200 of those people had developed cardiovascular disease. The authors found that patients who reported the highest loneliness scores had a 26% higher risk of developing heart disease.

Notably, social isolation without loneliness wasn't associated with any cardiovascular problems in the study.

Loneliness has previously been linked to a higher risk of heart disease in patients without diabetes.

Patients with diabetes are already at an increased risk of developing cardiovascular disease. A January study published in diabetes medical journal Diabetologia found that loneliness may increase a person's likelihood of developing type 2 diabetes, too.

US surgeon general Vivek Murthy said in a May report that a lack of social connection has similar impacts on human health to smoking up to 15 cigarettes a day.

"Given the profound consequences of loneliness and isolation, we have an opportunity, and an obligation, to make the same investments in addressing social connection that we have made in addressing tobacco use, obesity, and the addiction crisis," Murthy said in the report.

Dr. Lu Qi, one of the authors of the Tulane study and professor at Tulane University School of Public Health and Tropical Medicine, said people with diabetes should prioritize quality connections over the number of social engagements to protect their heart health.

He suggested that patients with diabetes be assessed for loneliness as a standard practice, so those patients can be referred to mental health services when needed.

"We should not downplay the importance of loneliness on physical and emotional health," he said. "I would encourage patients with diabetes who feel lonely to join a group or class and try to make friends with people who have shared interests."