High Blood Sugar and Heart Attack Complications

By Richard Asa @Rick Asa
April 12, 2016

Your arteries contract during a heart attack, making the aftermath worse.

High glucose at the time of a heart attack could make a coronary artery blockage more severe, causing your damaged blood vessel to contract.

That, in turn, could lead to increased complications from a heart attack, according to researchers. The blood glucose level could be high enough to increase problems just from a large meal.


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Many previous studies have suggested the link between high blood sugar and heart disease in people with diabetes compared to those without diabetes. Women with diabetes had a higher risk of heart disease when compared with those in the same age range who did not have diabetes.

But this is the first study to show “direct evidence of blood vessel contraction (due) to glucose, and the potential mechanism behind this contractile response,” said Richard Rainbow, a lecturer in cardiovascular cell biology at the University of Leicester. (In fact, another study found that giving insulin, which lowers blood glucose levels, after a heart attack significantly decreases the amount of inflammation in blood vessels and can improve survival.)

Since this was an experimental lab study, the researchers can draw conclusions only about cause and effect in a controlled environment. In the real world, the results underscore your need to have your blood sugar tested periodically and try to reduce high levels through exercise and diet.

The glucose connection to the higher risk for complications following a heart attack lies in the fact that blood vessels normally contract and relax to control blood pressure. In general, the more contracted the blood vessels are, the higher your blood pressure.

Heart attacks occur when a coronary artery, which provides blood to the heart muscle to supply the required nutrients and oxygen, is blocked. High glucose at the time of a heart attack could make the block even worse, causing the artery to contract even further, leading to a higher risk of complications.


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The research team that worked on this study has a history of investigating the effects of glucose on the cardiovascular system, diabetes, and heart function. Previous research showed that high glucose from any cause, not just diabetes, was an indicator of a worse outcome following a heart attack.

Further research showed that glucose has potentially damaging effects on the normal function of the heart, such as arrhythmia and elimination of the built-in protective mechanisms that the heart can activate upon stress.

“Our studies (have shown) that glucose has an important physiological effect on the normal functioning of the cardiovascular system,” Rainbow said. “Increases in blood sugar to pathophysiological levels cause marked changes in normal blood vessel and cardiac muscle behavior that would be life-threatening if left untreated.”

The research on glucose and its impact on increased heart attack complications opens the door for the development of drugs that could improve your outcome after a heart attack.

“This team has shown that, in multiple species, it is possible to use (protein Kinase C) as a target to block blood vessel constriction caused by high levels of glucose in the blood,” said Jeremy Pearson, associate director of the British Heart Foundation. “This opens the possibility for improved treatment for patients where recovery from heart attack is complicated by raised glucose levels.”

It’s already known that if you have diabetes you are “two to four times” more likely to develop cardiovascular disease than people without diabetes, according to the World Heart Federation. Cardiovascular disease is the leading cause of death for people with diabetes.

Uncontrolled diabetes damages your body’s blood vessels, making them even more vulnerable to hardening of the arteries and high blood pressure.


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February 28, 2020

Reviewed By:  

Christopher Nystuen, MD, MBA