Patients at high risk of diabetes also have an increased likelihood of heart disease - but not because of higher sugar levels, new research has found.
Researchers at the University of Glasgow say the trend is due largely to a higher prevalence of other heart disease factors such as obesity and high blood pressure.
The study involving more than 370,000 patients looked at their measurements of HbA1c, or average blood glucose levels, over two to three months.
It aimed to establish whether knowing HbA1c levels - increasingly measured in diabetes screening - could improve the assessment of patients' heart disease risk.
The team concluded while people at risk of diabetes are, on average, around 80% more likely to develop heart disease compared with those with normal HbA1c levels, such risk is not largely driven by higher blood glucose levels.
It is rather the prevalence of other heart disease risk factors such as age, blood pressure, smoking and body mass index (BMI).
Professor Naveed Sattar, from the University 's Institute of Cardiovascular and Medical Sciences, said: "We found that while assessing HbA1c levels adds minimally to cardiovascular risk prediction, those patients at risk for diabetes should have their heart disease risk factors appropriately measured and managed using conventional methods.
"Doctors, therefore, should make sure such patients are properly checked for all risk factors as then the patient can better know all their risks and be more motivated to make lifestyle changes which may lessen all these risks."
He added: "We believe this study will have practical implications for clinical practice because, in those patients without known diabetes, knowing HbA1C levels is unlikely to help predict heart disease risk.
"And in those patients at high risk for diabetes, heart disease risk assessments should continue to be done by conventional methods, with comprehensive lifestyle advice given to address both risks."
The paper is published in the journal Diabetes Care.
