Over time, elevated blood sugar levels damage blood vessels, nerves, and other internal structures. Complex sugar-based substances build up in the walls of small blood vessels, causing them to thicken and leak. As they thicken, they supply less and less blood, especially to the skin and nerves. Poorly controlled blood sugar levels also tend to cause the blood levels of fatty substances to rise, resulting in accelerated atherosclerosis (the buildup of plaque in blood vessels). Atherosclerosis is between two and six times more common in diabetics than in non-diabetics and occurs in both men and women. Poor circulation through both the large and small blood vessels can harm the heart, brain, legs, eyes, kidneys, nerves, and skin and makes healing injuries slow.
For all of these reasons, people with diabetes may experience many serious long-term complications. Heart attacks and strokes are more common. Damage to the blood vessels of the eye can cause loss of vision (diabetic retinopathy). The kidneys can malfunction, resulting in kidney failure that requires dialysis. Damage to nerves can manifest in several ways. If a single nerve malfunctions (mononeuropathy), an arm or leg may suddenly become weak. If the nerves to the hands, legs, and feet become damaged (diabetic polyneuropathy), sensation may become abnormal and tingling or burning pain and weakness in the arms and legs may develop. Damage to the nerves of the skin makes repeated injuries more likely because the person can’t sense changes in pressure or temperature. Poor blood supply to the skin can also lead to ulcers, and all wounds heal slowly. Foot ulcers may become so deep and infected and heal so poorly that part of the leg may need to be amputated. Recent evidence has shown that complications of diabetes can be prevented, delayed, or slowed by controlling blood sugar levels. Other unknown factors, including genetic ones, also determine the subsequent course of events.
Long-term Complications of Diabetes
|Tissue or Organ Affected||
|Blood vessels||Atherosclerotic plaque builds up and blocks large or medium-sized arteries in the heart, brain, legs, and penis. The walls of small blood vessels are damaged so that the vessels do not transfer oxygen normally and may leak||Poor circulation causes wounds to heal poorly and can lead to heart disease, stroke, gangrene of the feet and hands, impotence, and infections.|
|Eyes||The small blood vessels of the retina become damaged||Decreased vision and, ultimately, blindness|
|Kidneys||Blood vessels in the kidney thicken; protein leaks into the urine; the blood isn’t filtered normally||Poor kidney function; kidney failure|
|Nerves||Nerves are damaged because glucose isn’t metabolized normally and because the blood supply is inadequate||Sudden or gradual weakness of a leg; reduced sensations, tingling, and pain in the hands and feet; chronic damage to nerves|
|Autonominc nervous system||The nerves that control blood pressure and digestive processes become damaged||Swings in blood pressure; swallowing difficulties and altered gastrointestinal function, with bouts of diarrhea|
|Skin||Poor blood flow to the skin and loss of feeling result in repeated injury||Sores, deep infections (diabetic ulcers); poor healing|
|Blood||White blood cell function is impaired||Increased susceptibility to infection, especially of the urinary tract and skin|
|Connective tissue||Glucose isn’t metabolized normally, causing tissues to thicken or contract||Carpal tunnel syndrome; Dupuytren’s contracture|