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Blood sugar levels and diabetes

Blood glucose levels, often called blood sugar levels, are an important part of checking that diabetes is well managed.

Over time, high sugar levels associated with diabetes damage the body and can lead to other health problems.

If blood glucose levels are too high, this is called hyperglycaemia. If they are too low, it is called hypoglycaemia. Both extremes are best avoided and a person with diabetes will use treatments such as tablets, diet, exercise or insulin to try to keep the readings within target levels.

Guideline targets vary depending on age and the type of diabetes, but a doctor may suggest specific targets for individual patients.

Blood glucose readings can be done at home with a special meter and test strips. Some allow results to be downloaded to a computer to help show trends in glucose control.

Children with type 1 diabetes

  • Before meals: 4–8mmol/l
  • Two hours after meals: less than 10mmol/l

Adults with type 1 diabetes

  • Before meals: 4–7mmol/l
  • Two hours after meals: less than 9mmol/l

Type 2 diabetes

  • Before meals: 4–7mmol/l
  • Two hours after meals: less than 8.5mmol/l

Sugar and your body

Why are high blood sugar levels bad for you? It turns out your body doesn't have much of a sweet tooth. Glucose is precious fuel for all the cells in your body - when it's present at normal levels - but persistently high sugar levels behave like a slow-acting poison.

  • High sugar levels slowly erode the ability of cells in the pancreas to make insulin. The pancreas overcompensates, though, and insulin levels remain overly high. Gradually, the pancreas is permanently damaged.
  • All the excess sugar is modified in the blood. It becomes a form that sticks to and coats bloodstream proteins, which are normally "sugar-free." Thanks to this sugary film, the proteins don't function well, can be deposited in blood vessels, and can cause damage to them.

Because high sugar levels are everywhere, the body can be damaged anywhere. Damage to blood vessels, in particular, means no area is safe from too much sugar. High sugar levels and damaged blood vessels cause the multitude of complications that can come with diabetes:

  • Kidney disease or kidney failure, requiring dialysis
  • Strokes
  • Heart attacks
  • Visual loss or blindness
  • Immune system suppression, with increased risk for infections
  • Erectile dysfunction
  • Nerve damage, called neuropathy, causing pain or decreased sensation in the feet, legs, and hands
  • Poor circulation to the legs and feet, with poor wound healing

In extreme cases, because of the poor wound healing, amputation is required.

Keeping sugar levels closer to normal can prevent many of the complications of diabetes.

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WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on September 08, 2014

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