High blood sugar causes changes in hormones and cells that can damage blood vessels or nerves, or both. Damaged blood vessels are more likely to build up plaque, increasing the risk of coronary artery disease, heart attack, and stroke. When large blood vessels are affected, complications are called macrovascular disease. Damage to small blood vessels can lead to loss of vision, kidney disease, and nerve problems throughout the body. When small blood vessels are affected, the condition is called microvascular disease.
Blockages in the heart or brain increase the risk of heart attack or stroke. When the large blood vessels in the legs are affected (peripheral arterial disease), blood circulation to the legs and feet is reduced, causing changes in skin color, decreased sensation, poor wound healing, and leg cramps.
Diabetic retinopathy refers to complications affecting the eyes.
Diabetic nephropathy affects the kidneys.