With more damage, capillaries clot and, in response to blood deprivation, new vessels develop which bleed again and lead to scarring. Smoking and high blood pressure hasten these changes. Cataracts also occur more frequently in diabetics. Microscopic kidney changes cause tiny urine protein leakage as early as 5 years after onset of diabetes. End-stage kidney disease appears in 20 years.
Diabetes also damages nerves, sometimes of the eyes or the nervous system to the legs and feet.
It also affects the nerves to the stomach, the intestine, the heart, the bladder and, in men, combines with blood vessel damage to prevent erections. Aches and tingling often wax and wane and are characteristically worse at night. Lack of feeling can lead to unfelt but serious damage to the feet and ulcers, which can become chronically infected, requiring amputation. Coronary artery disease occurs sooner and more severely in diabetics than in healthy people. Heart attack mortality is higher.