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Diabetes Knowledge

Why is high blood sugar bad?

11/16/2018 by mySugr

Why is high blood sugar bad?

Diabetes is called the “silent killer” because once symptoms appear, the damage has already started. But why does high blood sugar cause all these problems in the first place?

The Basics

First, why does it happen? Your digestive system moves glucose (sugar) from your food to your bloodstream. In non-diabetics, insulin carries this into your cells. If there isn’t enough insulin or your cells have stopped responding to it, that glucose stays in your bloodstream. It’s a little like leaving your groceries out in the kitchen because you’re either too tired to do it (low insulin) or your cabinets and fridge won’t open well (insulin resistance).


So what does it do? If you’ve ever touched a food that was sticky, chances are high that it was because there was sugar in it. When sugar gets wet, it likes to stick to things. Blood has a lot of water, so this makes the extra glucose stick to proteins and fats in your bloodstream in a process called glycation. At high blood sugar levels, your blood literally becomes like syrup.

In fact, this is exactly what an HbA1c test measures. It measures how much “sticky” hemoglobin (red blood cells) you have. Fingerstick blood sugar testing measures free-floating glucose, but an HbA1c test shows how well you’re controlling your sugar over the past 3 months or so.

Your body tries to minimize glycation when it can. Insulin moves sugar in cells properly, but if there is still excess sugar then your body will try to move it out through your urine. This is why excessive urination and thirst are early symptoms of diabetes. But as you know from touching sticky things, once the glucose has stuck to something it’s harder to remove.

A Slow Burn A metaphor sometimes used to explain the dangers is that the sugar crystallizes in your blood and that these crystals cut to your cells to create the long-term damage of diabetes. That’s not quite what really happens, but it gets the point across. High blood sugar over time causes long-term damage to your body, especially parts of your body that do not regenerate well like your eyes and nerves.

What’s actually happening is a set of very slow oxidation reactions. These reactions cause other byproducts called AGEs (advanced glycation endproducts) to form in your body. It is these AGEs that are doing the real damage. They have been implicated in many of the symptoms that make up later-stage diabetes like eye problems, nerve problems, kidney problems and more.

These AGEs come into contact with different structures in the body and create a reaction that causes damage. It’s very little at first, but it accumulates over time. This is why when the long-term symptoms start to appear there’s little that can be done.

However, some AGEs are known to be benign to the body and some people with diabetes seem to never develop late-stage symptoms despite having uncontrolled blood sugar. Studying these products, their effects, and how they may differ between people is part of the current edge of diabetes research.

The formation of AGEs and their consequences is the end stage of a long process that starts with how you control your blood sugar. If your blood sugar is at normal levels then your body can handle the extra glucose and minimize glycation and the formation of AGEs. Regular testing and changing your habits to control your sugars will reduce your HbA1c number over time and thus reduce the long-term damage that diabetes can cause your body.

So, test your sugars regularly, get your HbA1c checked, and work with your diabetes educator.


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