Diabetes damages the small blood vessels around the heart, and this might explain the link to heart attack, a new research suggests.
The new study – led by researchers at Technical University of Munich (TUM) in Germany – investigates the effect of diabetes on the small blood vessels, or capillaries, that surround the heart. Damage to these can affect the whole of the heart muscle.
The heart’s network of veins and arteries and small offshoots into capillaries can be compared to a road traffic network. If one small minor road is blocked, it has little effect on the whole network.
However, if more and more small side roads come to a halt, the traffic on the main roads and highways becomes denser and denser, and eventually, the whole system seizes up and a heart attack ensues.
The researchers suggest their findings show how diabetes can have this effect.
They compared samples of heart tissue taken from patients with and without diabetes who underwent heart transplants. The samples from patients with diabetes showed that their hearts had significantly fewer small blood vessels around them.
After running tests in the laboratory, the team also found high levels of blood sugar are linked to loss of pericytes – a type of cell that forms a protective layer around small blood vessels.
The team believes this layer stabilises the blood vessel and causes the blood vessels to break up when damaged
The researchers also studied the effect of blood vessel loss in pigs genetically engineered to develop type 1 diabetes that is like the human form. They found the same damage occurred in their hearts.
However, with the help of gene therapy, the team was able to increase production of a protein that stimulates the growth of pericytes. This led to new growth of lasting and functioning small blood vessels.
It will be some time before such a treatment is available for use in humans, note the researchers, who also point out how the findings reinforce the importance of diagnosing diabetes early.
One in four people with diabetes does not know they have the disease. First author Dr Rabea Hinkel, a cardiologist at TUM’s university hospital, concludes:
“Diabetes often remains undetected in patients for years or even decades. Over that long period, massive damage can occur.”