How does Diabetes cause impaired blood circulation?

How does high glucose level in blood lead to impaired blood circulation in the legs which in turn leads to gangrene?

It's pretty complicated, so I'll just let you read about it here:
http://en.wikipedia.org/wiki/Advanced_gl...

Needless to say, we diabetics should be very concerned with keeping our sugar as close to "normal" as we can.

Explaining complicated stuff is my forte, After all, I am Oldgraggyguy.

The villain is glucose. Glucose molecules in the blood act like little knives. They circulate in the blood, and when they get into the capillaries of your extremities, they cause small tears in the walls of the capillaries.

When the tears are repaired, scar tissue is created in the inside of the capillary.

When enough of this scar tissue is created, blood flow to the capillary is slowed down, then stopped.

When the blood flow is stopped, all of the cells that rely on the damaged capillary to supply blood no longer get the blood that they need. The cells need blood to supply oxygen and other nutrients, and to remove waste products.

The cells then die.

This process is repeated over and over until enough skin cells die that bacteria that are normally in the environment alight on the extremity and begin infecting it, including the bacteria that causes gangrene.

In the long term it causes damage to small blood vessels, which can eventually lead to blockage of those blood vessels. Here's a site with good info: