New research claims that nearly four million people in the UK may be unaware they are at high risk of heart disease.
One in three of those most at risk over the next 10 years remain undiagnosed, the study estimates.
A team from the University of Oxford screened more than 71,000 people aged over 18 across England, Wales and Scotland.
There are 7.9 million people in the UK who have been diagnosed with cardiovascular disease, or are known to be at risk of developing symptoms.
Screening plans are urgent
Plans are in place in England to screen everybody between the ages of 40 and 74 for cardiovascular disease.
"The findings of this new study, added to the fact that more than half a million people in the UK are unaware they have Type 2 diabetes, highlights the urgency and importance of the government's proposed screening programme," said Saranjit Sihota, Diabetes UK Head of Public Policy.
"80 per cent of people with diabetes die of heart disease so it's crucial this programme is rolled out quickly as early detection of both heart disease and diabetes could save the lives of thousands of people across the UK."