High blood sugar levels may reprogramme stem cells, leading to lasting increased risk of fat, cholesterol and other substances narrowing arteries and restricting blood flow, research suggests.
University of Oxford researchers found that high blood glucose, a hallmark of diabetes, alters stem cells in the bone marrow that go on to become white blood cells called macrophages.
As a result, these macrophages become inflammatory and contribute to the development of atherosclerotic plaques that can cause heart attacks.
Researchers say the findings explain why people with diabetes are at increased risk of heart attack, even after their blood glucose levels are brought back under control – a mystery that has troubled doctors for years.
Nearly five million people in the UK have diabetes, and adults with the condition have double the risk of having a heart attack.
The experts say these findings open new possibilities for treatments that could reduce the risk of heart and circulatory disease in people with diabetes.
Robin Choudhury, professor of cardiovascular medicine at the Radcliffe Department of Medicine, University of Oxford, led the research.
He said: “Our study is the first to show that diabetes causes long-term changes to the immune system, and how this might account for the sustained increase in the risk of heart attack.
“We need to change the way we think about, and treat, diabetes.
“By focusing too narrowly on managing a person’s blood sugar levels we’re only addressing part of the problem.
“Right now, people with diabetes aren’t receiving effective treatment for their increased risk of heart and circulatory disease.
“These findings identify new opportunities for preventing and treating the complications of diabetes.”
The team investigated the differences in white blood cells in people with and without type 2 diabetes.
They removed the white blood cells from blood samples and grew them in an environment with normal glucose levels.
Those from people with type 2 diabetes showed an exaggerated inflammatory response compared with the cells from people without the condition.
Researchers also extracted stem cells from the bone marrow of mice with and without diabetes and transplanted these into mice with normal blood glucose levels.
They found that bone marrow taken from diabetic mice remembered its exposure to high levels of glucose and as a result the mice receiving this bone marrow developed almost double the amount of atherosclerotic plaques.
When the team analysed this in more detail, they found that those that had developed from stem cells in the bone marrow of diabetic mice had been permanently altered to become more inflammatory.
Professor Sir Nilesh Samani, medical director at the British Heart Foundation, which funded the research, said: “While treatments for diabetes have improved, people with diabetes still have a higher risk of heart attacks.
“This research may provide part of the explanation for why this is the case and potentially pave the way for new treatments to reduce the risk of heart attack for the millions of people living with diabetes.”
The research is published in the Circulation journal.