Loneliness is linked to serious medical problems, including heart disease and early death. To look at the relationship between loneliness and type 2 diabetes, researchers followed more than 4,000 adults over the age of 65 years in England who did not have diabetes at the time they joined the research. Researchers measured loneliness using a special questionnaire, and then looked to see who developed diabetes and whether or not loneliness was a factor. Over more than 10 years, 264 people developed diabetes. Researchers found that loneliness is a risk factor for diabetes, even after considering other common risk factors like excess weight, high blood pressure, depression and alcohol intake. A fifth of adults in the United Kingdom and a third of adults in the United States report feeling lonely sometimes. The negative impact of loneliness on health could be huge, and could be made worse because of the COVID-19 restrictions. This study also demonstrates a clear difference between loneliness and social isolation. For example, isolation (or living alone) does not predict type 2 diabetes, but loneliness (defined by a person’s quality of relationships) does predict type 2 diabetes. This could be because loneliness is stressful, and stress can impact metabolism. As a result, it is important to help people form and experience positive relationships. This could be a useful tool in preventing type 2 diabetes.