Signs and Symptoms
Symptoms of diabetic neuropathy depend on the type of neuropathy and which nerves are affected. The prominent symptom of peripheral neuropathy is numbness and tingling that begins in the toes and feet and gradually progress up through the legs and to the hands and arms. Diabetic neuropathy may also cause diminished or altered sensation of pain and temperature in affected body parts (Feldman 2012c; Topiwala 2012). Some patients will also develop pain described as a burning, electrical sensation, or stabbing pain (Edwards 2008; American Diabetes Association 2012; Topiwala 2012). The symptoms are often worse at night (National Diabetes Information Clearinghouse 2009; Callaghan 2012a; Topiwala 2012; American Diabetes Association 2012). In severe, long-standing cases, diabetic neuropathy may also cause muscle weakness if motor neurons are affected (National Diabetes Information Clearinghouse 2009; American Diabetes Association 2012; Feldman 2012c).
Other forms of diabetic neuropathy can cause additional symptoms. Diabetics with autonomic neuropathy may experience digestive problems, such as heartburn, abdominal pain, bloating, nausea, constipation, diarrhea, or vomiting a few hours after eating (Morales-Vidal 2012; Vinik 2006; Edwards 2008; National Diabetes Information Clearinghouse 2009; Topiwala 2012). Diabetic neuropathy also may affect the nerves in the heart and those that regulate blood pressure, leading to dizziness or feeling faint after standing up (Giudice 2002; Edwards 2008; Topiwala 2012; Morales-Vidal 2012). Other cardiovascular symptoms include poor heart rate control, leading to either a fast or slow heartbeat, and a lack of increase in heart rate due to exertion (Morales-Vidal 2012; American Diabetes Association 2012). The nerves that serve the bladder are another commonly affected region; this may lead to urinary retention, incontinence, urinating while sleeping, pain upon urination, poor stream, or difficulty initiating urination, sometimes followed by urinary tract infections. Sexual dysfunction, which can manifest as erectile dysfunction or vaginal dryness may also result (Morales-Vidal 2012; Topiwala 2012; American Diabetes Association 2012). Diabetic neuropathy can also affect the nerves that supply the sweat glands, leading to unusually dry skin (American Diabetes Association 2012; Morales-Vidal 2012).
One of the most troubling complications of diabetic neuropathy is foot ulcers. People with diabetic peripheral neuropathy often have diminished sensation in their feet, which means they may not notice foot injuries (Edwards 2008; Callaghan 2012a; Feldman 2012c). When combined with the poor circulation that commonly afflicts people with diabetic neuropathy, these foot ulcers may heal poorly and become infected, which can lead to serious complications and require foot amputation. Diabetes is the leading cause of lower-extremity amputations, accounting for roughly 80 000 cases per year in the United States alone; approximately 15% of people with severe diabetic neuropathy will develop foot ulcers during their disease (Callaghan 2012a). Importantly, people with diabetes have 15 times higher risk of lower limb amputations than people with other diseases (Margolis 2011).