Friday 14 March 2008

Why can't you inject sucrose intravenously if a person has low blood sugar?

When a patient's blood sugar levels are extremely low, it is important to administer replacement sugar intravenously, rather than orally. This is because by injecting the sugar straight into the blood stream, you bypass the time-consuming and unreliably step of getting it absorbed by the intestine.

But we only ever administer glucose (the biological form is frequently known as dextrose - see this article). And, come to think of it, we only ever measure blood glucose levels; when we say a person's blood sugar is low, we mean that their blood glucose is low. Why?

The answer, of course, is that it is the common fate of any carbohydrate to become glucose. As we've covered here, although carbohydrates can range from massive polysaccharides to tiny monosaccharides, only monosaccharides are absorbed from the intestine. The body's enzymes simply breakdown any carbohydrate larger than this until its constituent single sugar units are left. (Of course, there are three common dietary monosaccharides - glucose, galactose and fructose - but the other two are converted into glucose by the liver, so any carbohydrate ends up as glucose.)

So why can't we administer sucrose intravenously? Well, sucrose is a disaccharide; it's two monosaccharides joined together (glucose + fructose), and since a disaccharide normally never reaches our bloodstream without being degraded into two monosaccharides first, our cells are simply unprepared for it. To put it bluntly, there isn't even a mechanism to get the sucrose inside a cell!

So, no, if your friend starts to feel dizzy from a low blood sugar level, you can happily fetch her some sucrose to eat (it's table sugar, by the way), but you can't inject it into her veins.

Alas.

5 comments:

  1. AWESOME ANWSER DUDE, YOU JUST HELPED ME WITH MY CHEMISTRY HOMEWORK.

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  2. MAY THE FOURTH BE WITH YOU

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  3. MAY THE FOURTH BE WITH YOU

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  4. Fructose is more coveted by the body than glucose.. That is untrue all carbohydrates become glucose lol sorry but please research this in depth and retract/replace your article about the falsehood after you correct this one.

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  5. Also, the only way to defeat disorders or diseases like diabetes is to get closer to the human diet which begins with being raw like every other God-created loving & fearing creature on this planet (right?).. Then add some herbs and focus on fruit. I'm not a Christian but God says it right there in Genesis that he gave us some plants and seed-bearing things aka fruit as our food.
    If that fails to convince you, take a gander at our anatomy & physiology compared to other creatures and you'll see simply we are closest scientifically and physically to other frugivorous species. Not carnivores nor omnivores nor even herbivores. Lastly look at the value & devalue of every food or Earthly substance when consumed & processed by our bodies and it'll become even clearer to all willing to be honest and open themselves to see the reality. Funny stuff huh?

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