Damage from diabetes

I understand that high blood sugar causes damage to nerves and blood vessels causing all sorts of complications, but I still haven’t figured out why? What is it about having too much sugar in your blood that is so harmful?
Thanks!

In people with diabetes, sugar (glucose) accumulates in the blood to very high levels. The excess glucose can attach to proteins in the blood vessels and alter their normal structure and function. One effect of this is that the vessels become thicker and less elastic, making it hard for blood to squeeze through.

Diabetic eye disease starts when blood vessels in the back of the eye (the retina) balloon out into pouches. Although this stage — called nonproliferative retinopathy — generally does not affect vision, it can progress to a more serious form called proliferative retinopathy. This occurs when damaged blood vessels close off and new, weaker vessels take their place. These new vessels can leak blood, which blocks vision. They can also cause scar tissue to grow and distort the retina.

Because the retina can be irreversibly damaged before you notice any change in vision, and because retinopathy can be effectively treated with lasers to minimize vision loss, the American Diabetes Association recommends screening for retinopathy yearly.

Kidney disease starts when the blood vessels in the kidney become leaky. These leaky vessels allow protein from the blood to be excreted with urine. (It’s this protein that doctors detect when they test for kidney function.) Eventually, some vessels collapse and place more pressure on those that remain. Under this increased load, the remaining blood vessels are also damaged and the kidney may fail. If the disease progresses to this point, a person may have to go on dialysis — where a machine performs the role of the kidney — or receive a kidney transplant.

Because of the serious consequences of kidney disease, the American Diabetes Association recommends screening for protein in the urine every year starting at the time of diagnosis, or five years after the diagnosis in Type 1 diabetics.

From : http://www.genetichealth.com/dbts_consequences_of_diabetes.shtml#Anchor1

Another thing to note is blood pressure and cholesterol/triglycerides. If those are high, that puts even more stress on small and large blood vessels already damaged by high blood glucose levels. Some doctors put people with type 1 on certain types of high blood pressure medication (ACE inhibitors, ARBs) even if bp isn’t high because those drugs can help protect the kidneys.

Great answers, Jennifer and Kelly. Thanks for posting!

thank youu, it finally makes sense!!