Diabetic Neuropathy

Diabetic

Diabetic neuropathy is the most common complication of diabetes mellitus (DM), affecting as many as 50% of patients with type 1 and type 2 DM. Diabetic peripheral neuropathy involves the presence of symptoms or signs of peripheral nerve dysfunction in people with diabetes after other possible causes have been excluded.

Signs and symptoms

In type 1 DM, distal polyneuropathy typically becomes symptomatic after many years of chronic prolonged hyperglycemia, whereas in type 2, it may be apparent after only a few years of known poor glycemic control or even at diagnosis. Symptoms include the following:

• Sensory – Negative or positive, diffuse or focal; usually insidious in onset and showing a stocking-and-glove distribution in the distal extremities
• Motor – Distal, proximal, or more focal weakness, sometimes occurring along with sensory neuropathy (sensorimotor neuropathy)
• Autonomic – Neuropathy that may involve the cardiovascular, gastrointestinal, and genitourinary systems and the sweat glands

Physical examination should include the following assessments:

• Peripheral neuropathy testing – Gross light touch and pinprick sensation; vibratory sense; deep tendon reflexes; strength testing and muscle atrophy; dorsal pedal and posterior tibial pulses; skin assessment; Tinel testing; cranial nerve testing
• Autonomic neuropathy testing – Objective evaluation of cardiovagal, adrenergic, and sudomotor function in a specialized autonomic laboratory; may be preceded by bedside screening to assess supine and upright blood pressure and heart rate, with measurement of sinus arrhythmia ratio

Two classification systems for diabetic neuropathy are the Thomas system and the symmetrical-versus-asymmetrical system. The Thomas system (modified) is as follows:

• Hyperglycemic neuropathy
• Generalized symmetrical polyneuropathies
• Sensory neuropathy
• Sensorimotor neuropathy
• Autonomic neuropathy
• Focal and multifocal neuropathies
• Superimposed chronic inflammatory demyelinating polyneuropathy