Feet pain in diabetics
Aziz Shaibani, MD
Clinical Professor of medicine, Baylor College of Medicine.
Director, Nerve and Muscle Center of Texas.
Diabetes is the most common metabolic disorder in America. Over the years, diabetes affects the functions of many organs such as kidneys, heart, brain, eyes and nerves.
It is the most important risk factor for strokes and heart attacks and one of the most common causes of renal failure and blindness.
The most common cause of neuropathy in the USA is diabetes followed by alcoholism.
Neurologically, 50% of diabetic develop damage to the peripheral nervous system, (neuropathy). Every year, about 90,000 non-traumatic legs amputations are performed in the USA, mostly diabetes related. It is not very clear how diabetes causes neuropathy but it is very likely that there are different mechanisms including inflammation and metabolic induced damage. There are a least 10 types of diabetic neuropathies; the most common is the one that presents with feet pain, tingling and numbness. 10% of diabetic neuropathies are painful but these are the most disabling ones since they impair function and medications used to treat them often cause side effects like sleepiness and fatigue.
Neuropathy also may affect the nerves that supply the internal organs (stomach, genitals, urinary bladder, heart, etc). This is called diabetic autonomic neuropathy and it causes postural lightheadedness, urinary incontinence, impotence, diarrhea, early fullness, nausea, and impaired sweating.
A unique form of diabetic neuropathy causes severe thigh pain and weakness and may spread to the other side in 30% of cases. These patients are difficult to diagnose and they usually undergo back surgery because of the suspicion of lumbar disc disease. This kind of neuropathy is caused by inflammation and the good news is that it is self limiting but it may take up to 2 years for maximum recovery.
In the USA, There are no approved medications that can alter the natural course of neuropathy. Two medications are FDA approved to treat the pain of diabetic neuropathy, which are; Duloxetine and Pregabalin. These medications are at best effective in 50% of cases and even so, they may not cut the pain more than 50%. Therefore, there is a need for more effective agents.
The nerve and muscle center of Texas has been involved in diabetic neuropathy clinical trials since 1998 and has investigated more than 50 agents.
Currently, we are investigating a local clonidine cream that is supposed to have much less systemic side effects because it works locally. Also we will soon start a trial on an agent that is taken orally to reduce the pain of diabetic neuropathy.
These trials are placebo controlled and therefore, there is a 25%-50% chance that a placebo will be administered. It is more effective to screen patients over the phone to save them unnecessary visits to the center.
Other than medications, there are measures that help reduce risk of neuropathy and its complications such as; good diabetes control, and proper feet care.
Daily inspection of feet for ulcers, removing calluses and patients education about neuropathy are all-important.
An important challenge that is faced by physicians who treat neuropathy is to sort our diabetic from non-diabetic neuropathies in diabetic patients. Obviously, diabetes does not protect against the many other types of neuropathies that may present similarly. Some of these neuropathies are treatable.
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