Reducing the risk to the heart and blood vessels for people with diabetes

Diabetes can damage blood vessels putting people at risk of developing heart and circulatory diseases. For example, poor circulation in the legs (peripheral vascular disease) due to diabetes is the major cause of lower-limb amputation in the UK, and damage to small blood vessels in the eye (diabetic retinopathy) is the leading cause of blindness in people under 65. Since the 1970s, BHF-funded researchers at the University of Oxford have been at the forefront of research that is helping people with diabetes live longer, healthier lives.

Between 1977 and 1997, the BHF and a large group of other funders supported the UK Prospective Diabetes Study led by Professor Robert Turner and Professor Rury Holman at the University of Oxford. The study showed for the first time that heart and circulatory diseases, previously thought to be inevitable complications of having diabetes, could be delayed or prevented by improving blood glucose and blood pressure control in people with diabetes, starting as soon as they were diagnosed.

Showing that statins protect people with diabetes from heart and circulatory disease

The Heart Protection Study, which began in 1994, was based on more than 20,000 volunteers who were at risk of or already had heart or circulatory diseases. This was one of the largest trials we’ve ever funded, and was funded in partnership with the Medical Research Council.

Led by BHF Professor Rory Collins at the University of Oxford, the trial investigated whether using statins to lower ‘bad’ LDL cholesterol levels could reduce the risk of heart and circulatory diseases.

The study found that statins reduced the risk of heart attack and stroke by 25 per cent. The participants included 6,000 people with diabetes, and the statin also reduced their risk of heart and circulatory diseases by 25 per cent.

Based in large part on these findings, statins are now prescribed routinely to people diagnosed with diabetes.

Testing aspirin and fish oil supplements

We also funded a large study to understand whether aspirin should be prescribed routinely to people with diabetes.

People who have had a heart attack or stroke are often prescribed a daily low dose of aspirin. This can help prevent the formation of blood clots that can cause heart attacks and strokes. But aspirin can have side effects, such as an increased risk of bleeding. So it was unclear whether aspirin should be routinely prescribed for people with diabetes, who are at higher risk of heart attacks and strokes. Between 2005 and 2011, we funded the ASCEND trial led by Professor Jane Armitage and Professor Louise Bowman at the University of Oxford. It showed that aspirin reduces the risk of heart and circulatory problems but also increased the risk of major bleeds, mainly from the stomach and intestines, so overall there was no clear benefit. This large trial provided conclusive evidence that doctors should not recommend taking a daily aspirin to prevent heart and circulatory problems in people with diabetes.

The ASCEND trial also tested whether a fish oil supplement could reduce heart and circulatory diseases in people with diabetes. The results of the trial suggested that it does not. People in the UK spend approximately £60 million a year on fish oil supplements, and there are also some concerns about the environmental impact of some of these supplements. The results of this study support the idea that people should instead focus on having a healthy diet - including oily fish - to help protect their heart health.

These decades of BHF-funded research have helped doctors to understand more about how to support the 4.1m people diagnosed with diabetes in the UK to live longer and healthier lives.

First published 1st June 2021