Long-term Complications of Diabetes
The Long-Term Effect of High Blood Sugars
The long-term or chronic effects of diabetes include significant and permanent damage to a variety of organs and tissue, but most directly the kidneys and the nerves and blood vessels that feed the eyes, limbs and gastro-intestinal tract . These effects are known as microvascular complications because the injury to these organs stems from damage to the tiny blood vessels that feed these tissues and nerves. These complications can begin to develop early in the diagnosis of diabetes but generally take years to become clinically significant.
There are also non-sugar related effects of diabetes mellitus which include heart disease, stroke, and peripheral vascular disease. Having diabetes increases the risks of these medical problems substantially. These are called macrovascular complications.
The likelihood that these microvascular complications will arise seem to increase with the duration and severity of the diabetes- those with very high blood sugars for many years have a much higher chance of already having or developing microvascular complications than those with mild, new-onset diabetes. Even more importantly, studies have shown that controlling high-blood sugars with diet, exercise and medication over the long-term can drastically reduce the chances of developing these complications.
Kidney damage from diabetes (known as Diabetic Nephropathy) is one of the most common and worrisome microvascular complications and is the most common cause of chronic kidney failure and the need for life-long dialysis in the United States . Generally it takes up to 10-15 years for clinically significant diabetic nephropathy to occur but . By the time damage to the kidneys from diabetes is detected (usually by way of testing the protein content of the urine), there has already been some irreversible damage to the filtration system of the kidneys. However, controlling blood sugar and using specialized blood pressure medications has been shown to drastically slow the progression of kidney damage from diabetes.
Diabetic Retinopathy or damage to the retina of the eyes related to high blood sugars is the leading cause of blindness in the United States. Regular monitoring by an eye specialist may detect early effects of high blood sugars to the eyes. Laser eye surgery is the mainstay of treatment for damaged retina related to uncontrolled diabetes; however, as in other microvascular complications, the injury to the eyes may take years to develop and strict blood sugar control has been shown to be a very useful preventative treatment for diabetic retinopathy.
Another common microvascular complication is Diabetic Neuropathy which involves injury to the nervous system related to diabetes. The most common symptom is tingling, burning or numbness to the legs and hands. This damage can lead to significant chronic pains and may predispose diabetics to developing loss of sensation and consequently unrecognized ulcers and wounds of the lower extremity.
With or without normalization of blood sugars, patient with diabetes mellitus have a much higher risk of heart disease than the average population. The diagram to the left shows that the risk of heart attack and stroke is about 20% over 10 years for a non-diabetic patient who already had a heart attack. A diabetes patient has the same 20% risk over 10 years.
Heart disease is caused by a narrowing or blocking of the blood vessels to the heart. The vessels normally carry oxygen and nutrients to the heart. These vessels can become partially or totally blocked by fatty deposits. The same process can occur in the brain which can cause strokes. Reduced blood flow in the legs leads to peripheral vascular disease which can be painful and cause ulcers on the leg.