Diabetic Neuropathy

Excess glucose activates the polyol pathway inside nerve cells, converting glucose into sorbitol and fructose. Accumulation of these substances causes cell swelling, triggers oxidative stress, disrupts nerve signaling, and weakens structural proteins. Advanced glycation end products further damage proteins and lipids, reducing the nerves' ability to repair themselves and accelerating degeneration.

Diabetes thickens basement membranes and narrows small blood vessels supplying nerves, reducing oxygen and nutrient flow to the vasa nervorum. This ischemia intensifies metabolic damage and worsens nerve dysfunction. Combined metabolic and vascular injury leads to demyelination, axonal loss, and impaired regeneration, slowing nerve conduction velocity and disrupting communication with target tissues.

Long sensory nerves are most vulnerable to damage from chronic hyperglycemia because they depend on efficient glucose metabolism and blood supply. Sensory nerve involvement leads to loss of pain, temperature, and vibration sensation, typically beginning in the feet and progressing upward in a glove and stocking distribution pattern characteristic of diabetic neuropathy.

Motor nerve damage causes weakness, muscle wasting, and foot deformities. Autonomic nerve damage results in cardiovascular instability, gastrointestinal motility disorders, bladder dysfunction, sexual dysfunction, and abnormal sweating. These complications significantly impact quality of life and represent important clinical manifestations requiring comprehensive management and monitoring.

Advanced glycation end products accumulate in nerve cells due to prolonged high blood sugar levels. These AGEs modify proteins and lipids, impairing repair mechanisms and accelerating nerve degeneration. This process compounds the metabolic injury already caused by sorbitol and fructose accumulation, creating a dual mechanism of nerve damage.

Nerves undergo demyelination and axonal loss, reducing conduction velocity and impairing communication between nerves and target tissues. These structural changes result from combined metabolic and vascular injury, leading to progressive nerve dysfunction and the characteristic sensory and motor deficits of diabetic neuropathy.

Diabetic neuropathy is one of several complications of diabetes mellitus arising from prolonged hyperglycemia. Understanding its pathophysiology helps explain how chronic high blood sugar damages multiple organ systems. Learning about complications of diabetes mellitus provides broader context for managing this serious endocrine disorder.