Diabetic Neuropathy: Types, Causes, and Risk Factors

OCTOBER 03, 2017
Diabetes is a serious condition that is defined by high blood sugar levels. An individual with diabetes is at risk for other conditions and comorbidities, one of the more common ones being diabetic neuropathy,1 a nerve disorder that typically develops over time. The condition can sometimes be asymptomatic but generally is accompanied by several unpleasant symptoms. Although there is a correlation with age, anyone with diabetes can develop neuropathy at any time, and it is, in fact, quite common. According to the National Institute of Diabetes and Digestive and Kidney Diseases 60% to 70% of people with diabetes have some form of neuropathy.

Types of Diabetic Neuropathies
There are 4 major types of diabetic neuropathies: autonomic, focal, peripheral, and proximal.

Autonomic diabetic neuropathy mainly affects the digestive tract but also causes damage to the blood vessels, urinary system, and sex organs. Those with autonomic neuropathy may experience a variety of gastrointestinal symptoms such as bloating, nausea, constipation, and/or diarrhea. If the neuropathy affects the blood vessels, it can cause blacking out when standing up too quickly, dizziness, and a faster heartbeat. In some cases, autonomic neuropathies have led to erectile dysfunction.

Focal neuropathy mainly affects the head, torso, and legs and may occur somewhat sporadically, causing double vision, aching behind one eye, and pain in a specific and localized part of the body.

Peripheral neuropathy mainly affects the feet and legs. Individuals with peripheral neuropathy may experience symptoms such as tingling, numbness, and pain. In some instances, people have reported a complete loss of feeling within their arms, hands, legs, as well as ulcers, infections, deformities, and bone and joint pain.

Proximal neuropathy affects the thighs, hips, buttocks, and legs and is typically unilateral. It often causes trouble standing up after sitting for long periods and requires the individual to get assistance while doing simple day-to-day activities.  
Causes of Diabetic Neuropathy
Excessive high blood sugar is thought to be the biggest cause of diabetic neuropathy, as elongated blood glucose levels can cause damage to nerve fibers throughout the body. There is no specific reason as to why or how this happens, but an interaction between the blood vessels and nerves has been observed. It is known, however, that high blood sugar levels avert the nerves' capability of transmitting signals. High blood sugar also tends to decrease the amount of oxygen that is supplied to the nerves, which weakens their ability to do anything.

Smoking and alcohol intake are other factors that are suspected of contributing to neuropathy as they tend to also decrease the amount of oxygen that goes to nerves throughout the body. Cigarettes can also cause damage to the blood vessels and weaken the walls, with limited oxygen transportation as well. Those who smoke and ingest a lot of alcohol also tend to have weakened immune systems, causing them to be more susceptible to developing neuropathy. Several genetic factors that are unrelated to diabetes are suspected of playing a role, as well, but not much evidence has been found to support this theory.

Risk Factors and Complications
The biggest risk factor of neuropathy is poor blood glucose control, but several other factors come into play. For instance, age plays a role, and the older one gets, the more likely it is that diabetic-related neuropathy can occur. Those who have had diabetes for a long time are also risk, as there is a correlation between neuropathy and the duration of the condition. Smoking is a risk factor, as is kidney damage, which can limit the proper excretion of certain toxins and lead to nerve damage. Individuals with diabetic neuropathy tend to develop complications, such as sexual dysfunction, urinary tract problems, digestive issues, and orthostatic hypotension. Dietary changes are often made to relieve some of these complications, but most are unavoidable when blood glucose values are unstable.

Prevention and Treatment2
The best advice concerning prevention is to monitor blood glucose levels. Sometimes, developing diabetes is unavoidable but it is important to manage the condition as best as one can. This means trying to keep blood glucose levels in range by eating right, exercising, and taking medication every day, as directed by a doctor. Unfortunately, the condition has no known cure, but the goal of treatment is to slow the progression. There are medications to help people manage the condition, such as pain-relieving medications and antidepressants. There are also several medications that can help solve complications such as urinary problems and sexual dysfunction.

1. National Institute of Diabetes and Digestive and Kidney Diseases. Nerve damage (diabetic neuropathies). niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathies. Published 2013. Accessed October 3, 2017.

2. American Diabetes Association. Standards of medical care in diabetes – 2016 abridged for primary care providers. Clin Diabetes. 2016;34(1):3-21. doi: 10.2337/diaclin.34.1.3.

Shelby Leheny, Pharm D, B.S
Shelby Leheny, Pharm D, B.S
Shelby Leheny received her Doctor of Pharmacy Degree from Lake Erie College of Osteopathic Medicine (LECOM) and her Bachelor's of Science degree at the University of Pittsburgh. She is a pharmacist at CVS.