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How High Sugar Level in Blood Damages the Blood Vessels

By Vicki Mozo

Damage in the vasculature is common in individuals who have high sugar level in blood. It seems that an excess of blood sugar is causing damage to the vasculature by impairing the function of the blood vessels. Thus, a fundamental question emerges, how does an excess of glucose damage vasculature?

The link between excess blood glucose and vasculature damage is partly explained through the study conducted by a research team headed by Dr. Rita C. Tostes of the MCG School of Medicine (1). Their findings seem to elucidate how a consistently high blood glucose level leads to vasculature damage.

In order to understand how high sugar level in blood causes harm to the blood vessels, it is important to know what blood glucose is and what an excess of blood sugar means.

What is blood glucose?

Glucose is a major form of sugar found in the body. It serves as an important source of energy that fuels a number of metabolic processes. Blood glucose is a term used to refer to the glucose present in blood. The blood acts as a medium to transport glucose molecules in different parts of the body because of its essential role in metabolism.

When is blood glucose an excess?

Blood glucose level pertains to the amount of glucose in blood. The normal sugar level in blood in healthy individuals ranges between 70 and 125 mg/dl in average. Therefore, a blood glucose level that is higher than these values means that there is an excess glucose in blood. If blood glucose level is consistently high (e.g. above 150), the condition is called hyperglycemia.

How does an excess in blood glucose damage vasculature?

When a person eats, the food is digested into smaller, simpler forms. Thus, complex carbohydrates in the diet are digested to produce simpler forms such as glucose. The glucose molecules then make their way through the blood vessels into the bloodstream. Insulin hormones are released to regulate the amount of glucose in blood. If this function of insulin is impaired, hyperglycemia occurs.

Tostes found that when blood glucose levels have been high for so long, the blood vessels could not relax or dilate. It is because vasodilators such as nitric oxide in blood vessels have become less in number. Instead of the nitric oxide, the sugar moiety O-linked N-acetylglucosamine (O-GlcNAc) molecules have increased in number.

O-GlcNAc molecules are monosaccharides derived from glucose. They are capable of modifying proteins via a process that competes with the phosphorylation in the vasculature. Phosphorylation is a vital process in the vasculature because it is used during the production of nitric oxide.

If there is an excess of glucose in blood, more O-GlcNAc are formed. The more O-GlcNAc, the less nitric oxide are produced in the vasculature. Without enough nitric oxide, the blood vessels could not loosen up. They would remain contracted for so long that ultimately the passage of blood through these vessels would become difficult.


High sugar level in blood is unhealthy because it leads to vasculature damage. Poor circulation due to damaged blood vessels increases the risk of stroke, heart attacks, chronic wounds, and amputations. Hence, people should keep a healthy sugar level in blood at all times.



1New evidence of how high glucose damages blood vessels could lead to new treatments. (2009, May 11). Retrieved from http://news.mcg.edu/archives/1930

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