More than 11 million uninsured adults have at least one chronic condition, including cardiovascular disease, hypertension, diabetes, or chronic obstructive pulmonary disease, according to a study in Tuesday’s Annals of Internal Medicine.

These uninsured chronically ill people aged 18 to 64 are less likely than those with insurance to have visited a doctor in the past 12 months and are more likely to visit the emergency department for routine care. The study raises doubts about the assumption that many uninsured U.S. residents are young and healthy, researchers noted. The long-term care system often bears the burden for untreated chronic illnesses.

“We have made dramatic advances in treatment of chronic illnesses like heart disease and high blood pressure,” Andrew Wilper, the study’s lead author, said in a statement. “But many Americans are locked out of the system because they are uninsured and cannot afford this life-saving care.”