A new study led by researchers from University College London (UCL) and the London School of Hygiene & Tropical Medicine (LSHTM) has found that men and women with high blood sugar levels have a 30-50% higher risk of cardiovascular disease, even if their blood sugar levels are below the diabetic threshold.
The study, published in the Lancet Regional Health Europe journal, also found that among people with diagnosed diabetes, the trend toward a higher risk of cardiovascular disease in women compared to men disappeared when modifiable factors such as body measurements and medication use were taken into account.
The researchers found evidence that, as long as blood glucose levels were within the “normal” range, “lower is better” for preventing cardiovascular disease. Compared to those with normal blood glucose levels, those with the lowest blood glucose levels had a 10% lower risk of developing any form of cardiovascular disease. Meanwhile, men with blood glucose levels below the diabetic threshold had a 30% higher risk of cardiovascular disease, and women with blood glucose levels below the diabetic threshold had a 30-50% higher risk of cardiovascular disease. For those with diagnosed diabetes, the risk doubles.
The study analysed UK Biobank data from 427,435 people (54.2% women, 45.8% men) from the UK across the full range of blood glucose levels, including those in the ‘normal’ range, those with pre-diabetes and those with diabetes.
The researchers found that after adjusting for age, both men and women with moderately high blood glucose levels below the diabetes threshold were at increased risk of any cardiovascular disease, with the relative increase being greater in women than in men.
The difference in cardiovascular disease risk between men and women almost disappeared when the researchers took into account obesity, blood pressure medication and statin use.
The study found differences in the use of antihypertensive and statin therapy between men and women, with more men taking these medications than women. Women are not more likely to be prescribed these preventive medications than men with comparable blood sugar levels, the study found. Researchers say more research is needed to focus on the factors behind this “prescribing gap.”
Co-author Dr Victoria Garfield (from UCL’s MRC Lifespan Health and Ageing Unit) said: “One of the most striking findings was that compared with normal blood sugar levels, people with the lowest blood sugar levels had a lower risk of cardiovascular disease. This is in line with previous research from our group which found that being in the lowest blood sugar category may confer some benefits for brain health.”
Lead author Dr Christopher Lenci of LSHTM said: “This study represents a major advance in decades of research into diabetes and heart disease. We quantified the differences in heart disease risk between men and women across the full range of blood glucose levels. What we found was that these risks are not limited to those with diagnosed diabetes – men and women with pre-diabetes are also significantly affected. Our team also found compelling evidence that, within the ‘normal’ blood glucose range, lower blood glucose levels are more effective at preventing heart disease.”
Ruth Goss, senior cardiac nurse at the British Heart Foundation, which part-funded the research, said: “This large-scale study adds to what we know about the link between persistently high blood sugar levels and the risk of heart and circulatory disease. However, it’s important to note that this analysis did not include people with type 1 diabetes, so this cannot be applied to type 1 diabetes.
“Preventing future heart disease requires not just controlling your blood sugar levels, but also reviewing your entire lifestyle. Adopt a healthy lifestyle such as eating a balanced diet, exercising regularly and quitting smoking. Monitoring your risk factors for heart and cardiovascular disease, such as maintaining healthy blood pressure and cholesterol levels and managing your weight, can help reduce your risk of future heart and cardiovascular disease.
“If you’re aged between 40 and 74, you can request an NHS health check in England, and similar schemes are available in the rest of the UK. This will tell you if you’re at increased risk of heart and circulatory disease and help you identify and address any associated risk factors.”
Dr Lucy Chambers, head of research and communications at Diabetes UK, said: “Diabetes is responsible for more than 770 strokes, 590 heart attacks and 2,300 cases of heart failure every week, and we know that women are particularly at risk of poor outcomes. “This important new research, jointly funded by Diabetes UK and the British Heart Foundation, highlights strategies that can address gender inequalities in cardiovascular disease outcomes, such as greater use of antihypertensive drugs and statins in women.
“This study is also an important reminder that over the long term, higher than normal blood sugar levels can damage blood vessels and increase the risk of cardiovascular disease, and that this affects not only people with diabetes but also those with pre-diabetes.”
“If you have diabetes, it’s important to receive support from your healthcare team to lower your blood sugar and manage the risk of diabetes complications, including having an annual diabetes screening and test and discussing the medication options available to you.” If you’ve been diagnosed with pre-diabetes, your healthcare team can support you to make changes to lower your blood sugar levels and prevent or delay type 2 diabetes. Find out your risk of type 2 diabetes by completing Diabetes UK’s
About the study
Limitations of the study include that UK Biobank participants were healthier than the general UK population and that lifestyle data were self-reported.
The researchers conducted an observational follow-up study using data from UK Biobank. The final analysis included 427,435 participants, aged 40-69 years, recruited in England, Scotland and Wales between 2006 and 2010 and followed up until 2021, including 195,752 men (45.8%) and 231,683 women (54.2%).
The researchers classified participants according to standard clinical cutoffs: low-normal (<35 mmol/mol or <5.5%), normal (35-41 mmol/mol or 5.5-5.9%), prediabetes (42-47 mmol/mol or 6.0-6.4%), undiagnosed diabetes (≥48 mmol/mol or ≥6.5%), or diabetes confirmed by a previously validated algorithm combining medical history and use of hypoglycemic medications.
