Sugar not to blame for high risk of heart disease in those at high risk for diabetes

Patients at high risk for diabetes are also at a high risk for heart disease – but not because of higher sugar levels, according to new research led by the University of Glasgow. 


The research – published today in Diabetes Care – found that patients at a higher risk for diabetes also had higher heart disease risks, but that this was due largely to a higher prevalence of other heart risk factors such as obesity, higher blood pressure levels and abnormal lipids.

The study looked at over 370,000 patients from the UK Biobank, making it the largest single cohort reported to date using patients’ measurements of HbA1c – average blood glucose (sugar) levels over 2-3 months.

The researchers wanted to assess whether knowing HbA1c levels – which are increasingly measured in screening for diabetes to assess risk – could improve heart disease risk assessment.  

The researchers found that the near two-fold higher risk for heart disease for those at higher risk of diabetes was driven mainly by abnormal levels of conventional heart disease risk factors. “On average such people were around 10kg heavier, and their blood pressure was already 6 units higher. More also smoked so they had many other reasons to be at higher risk, well before their sugar levels rose into the diabetes range.” 

This means that whilst people at risk for diabetes are, on average, at around an 80% greater heart disease risk compared with those with normal HbA1c levels, such risk is not largely driven by elevated HbA1c, but rather by differences in the prevalence or levels of other established heart disease risk factors, such as age, blood pressure, smoking, lipid levels, and BMI.

Professor Naveed Sattar, of the University’s Institute of Cardiovascular and Medical Sciences, said: “In our study, we found that whilst 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, ‘Glycated hemoglobin, prediabetes and the links to cardiovascular disease: data from UK Biobank' is published in Diabetes Care. The study was funded by a grant from Chest, Heart, and Stroke Scotland.

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First published: 19 December 2019