High sugar levels cause damage to the nerves in your feet. This is called peripheral neuropathy. It can make your feet less sensitive to pain, lead to deformities of your feet, and cause dryness of your skin.
High sugar levels also damage the blood vessels in your feet. This is called peripheral vascular disease and means that the blood supply to your feet is reduced.
Peripheral neuropathy and peripheral vascular disease can cause problems.
If you damage your foot in any way, for example by stepping on something, or getting a blister from a pair of shoes, you may not feel any pain. This means the damage could get worse without you realising. If the blood supply to your foot is poor as well, the wound may not heal very well.
Very quickly, a small area of damage can get worse, forming an ulcer or an infection that could affect your whole body. Unfortunately, this may lead to you needing an amputation of part of your foot or leg.