Damage to the Kidneys
Diabetes is the most common cause of kidney disease, according to the National Kidney and Urologic Diseases Information Clearinghouse. Kidneys are responsible for filtering waste products out of the blood and keeping proteins in the body. Diabetes damages the kidneys by damaging the glomeruli, the filtering agents of the kidneys. Over time, high blood sugar makes the glomeruli too porous, and protein is lost through the urine (proteinuria). Excess fluid is retained, waste products accumulate in the body and blood pressure rises, because the kidneys help keep blood pressure under control by controlling excess fluid (edema). High blood pressure, which can also be a side effect of diabetes' damage to blood vessels, further damages the kidneys. Keeping very tight control on blood sugars reduces the risk of protein being lost in the urine by 1/3, according to the American Diabetic Association.
Damage to the Eyes
Diabetes is the top cause of blindness in the United States, according to the Centers for Disease Control (CDC). Eye damage from diabetes is called diabetic retinopathy. High blood sugar damages blood vessels in the eyes in several ways. The smallest blood vessels, the capillaries, are damaged by high blood sugar and will begin to leak (microaneurysms). High blood sugar also causes blockages in veins and arteries, which can decrease oxygen delivery to the eyes. When this happens, abnormal blood vessels may grow in an effort to supply more oxygen to the eyes. The new vessels are fragile, break and leak, which can cause swelling in the macula, the center of vision.
All of these changes can cause vision loss. Diabetic retinopathy can be non-proliferative (NPDR), with small bleeds and leakages, or proliferative, with growth of new blood vessels, leaking and scarring.
Damage to the Feet
Diabetes hurts feet by injuring the nerves that relay pain signals to the feet, as well as through blood vessel damage it causes throughout the body. Pain is a valuable signal that warns us when something is wrong and we need to fix it. Diabetic neuropathy breaks that signal by dulling the sensations that warn of problems. According to the National Diabetes Information Clearinghouse, the most common type of diabetic neuropathy is peripheral neuropathy, which affects the arms, legs, hands, feet, fingers and toes.
To make matters worse, the circulatory damage high blood sugar causes, paired with high blood pressure, leads to less blood flow and oxygen delivery to the feet, meaning that small injuries are less likely to heal well. So a small cut, a foot ulcer, or an injury that would normally be noticed and treated goes undetected and becomes much worse. Severe infection can lead to loss of toes, feet or legs in diabetics.
