Diabetic Peripheral Neuropathy (DPN) is the most common chronic complication of diabetes. This condition involves the progressive damage of peripheral nerves—those outside the brain and spinal cord—most often affecting the feet and legs. DPN is highly prevalent, affecting approximately 50% of people with long-term diabetes. This chronic nerve damage can lead to sensory loss, persistent pain, foot ulcers, and subsequent lower-limb amputation worldwide.
How High Blood Sugar Damages Nerves
Chronic exposure to elevated blood glucose levels (hyperglycemia) initiates destructive metabolic changes within nerve fibers. One major pathway involves the diversion of excess glucose into the polyol pathway, converting glucose into sorbitol. Sorbitol cannot easily exit the nerve cells, causing it to accumulate and create osmotic stress. This stress draws water into the cell, leading to swelling and nerve damage.
The polyol pathway activation also depletes NADPH, a molecule essential for the cell’s defense against oxidative stress. Furthermore, chronic hyperglycemia damages the small blood vessels (vasa nervorum) that supply oxygen and nutrients to the nerves. This leads to reduced blood flow and localized ischemia. This combined process primarily affects the longest nerve fibers first, explaining why symptoms begin in the feet.
The Physical Signs of Nerve Damage
The physical presentation of DPN includes a range of sensory and motor disturbances, beginning in the extremities. Patients frequently describe numbness, tingling, burning sensations, or sharp, shooting pain in their toes and feet. This sensory loss progresses upward in a “stocking-glove” distribution, affecting the lower legs symmetrically before potentially reaching the hands and arms.
The loss of protective sensation is a dangerous aspect of DPN, as minor injuries or sores can go unnoticed and develop into severe ulcers. Some individuals may experience heightened pain sensitivity. Motor nerve damage, though less common early on, causes muscle weakness, particularly in the feet. DPN can also affect the autonomic nervous system, leading to issues like gastroparesis or orthostatic hypotension (a sudden drop in blood pressure upon standing).
Who Is Most Susceptible to Neuropathy
The duration of diabetes is a primary risk factor, as cumulative exposure to high blood sugar is directly correlated with nerve damage. The degree of blood sugar control, reflected by elevated hemoglobin A1C (HbA1c) levels, is a significant predictor of neuropathy development. Older age also increases susceptibility, as does the presence of other cardiovascular risk factors. Patients with co-existing conditions like hypertension, high cholesterol (dyslipidemia), and obesity have a greater chance of experiencing DPN, and smoking further compounds the risk by worsening circulation.
Managing the Condition and Preventing Further Damage
The most effective strategy for managing DPN is aggressive disease modification focused on maintaining tight glycemic control. Reducing blood sugar levels to target ranges can slow the progression of nerve damage and stabilize the condition. This modification typically involves a combination of medication, diet, and regular physical activity.
For patients experiencing neuropathic pain, symptomatic relief is managed through pharmacological options. Certain anti-seizure medications, such as gabapentin and pregabalin, and some antidepressant medications, including duloxetine, are commonly prescribed to modulate the pain signals. Beyond medication, preventing the devastating complications of DPN, especially foot ulcers, is paramount. Daily foot self-examinations, wearing specialized protective footwear, and receiving regular professional foot care are non-negotiable steps to prevent minor injuries from escalating to severe infections and possible amputation.