Healthy living

Blood protein linked to stroke in diabetes

Blood protein linked to stroke in diabetes Increases bleeding

Scientists have discovered why people with diabetes are more likely to experience severe strokes leading to greater damage.

When blood sugar levels are high - which happens in diabetes - a blood protein called plasma kallikrein inhibits the normal blood clotting process during a stroke, leading to more bleeding on the brain, the scientists suggested.

Strokes are caused by either a blood clot in a vessel stopping the flow of blood to the brain (ischaemic stroke) or by a burst blood vessel (haemorrhagic stroke). About seven out of 10 strokes are caused by blood clots.

Each year around 150,000 people have a stroke in the UK. It is the third most common cause of death after heart disease and the biggest cause of disability.

Past research has associated diabetes and raised blood sugar levels with increased bleeding on the brain during haemorrhagic stroke, but the reason for this is unclear.

Scientists from the Joslin Diabetes Centre in Boston reached their conclusion after injecting blood into the brains of rats with and without diabetes. The diabetic rats bled over a much greater area of the brain.

But when the diabetic rats were also injected with a molecule which inhibits the activity of plasma kallikrein, the amount of damage to the brain was similar to that in non-diabetic rats.

When pure plasma kallikrein was injected into the rats' brains, it rapidly increased major bleeding in the animals with diabetes but had little effect on those without the condition, the researchers wrote in the journal Nature Medicine.

The scientists say their work suggests that blood sugar levels at the time of having a stroke is the most important factor for the increased bleeding seen in diabetes patients.

They also suggest that the findings raise the possibility of developing drugs that target the blood protein.

"Given the prevalence of strokes and the damage they inflict, these findings are exciting because they suggest the possibility that rapid control of blood sugar levels may provide an opportunity to reduce intracerebral hemorrhage, which is a clinical situation that has very limited treatment options," said Dr. Edward Feener, who led the study.

"This work could have broad implications since about half of patients with acute hemorrhagic stroke have hyperglycemia, whether or not they have pre-existing diabetes."

This article was published on Mon 24 January 2011

Image © James Steidl -

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