Diabetic peripheral neuropathy

Disease Description (Causes and Symptoms)

Diabetic polyneuropathy is a complication caused by damage to peripheral nerves (mainly sensory nerves) due to long-term hyperglycemia. Pathophysiologically, hyperglycemia damages nerve fibers and microvessels, resulting in nerve ischemia, metabolic abnormalities, inflammation, and axonal degeneration. The main symptoms are as follows.

• Sensory abnormalities: numbness and tingling (especially starting at the toes and moving upward), loss of sensation, pins-and-needles sensations, burning sensations, and electric-shock-like pain
• Pain: burning sensations and aching pain that worsen at night (some patients have little or no pain)
• Increased risk of trauma and ulcer formation due to loss of sensation (calluses → ulcers caused by numbness in pressure areas of the feet)
• Autonomic symptoms (in some patients): blood pressure fluctuations (orthostatic hypotension), changes in heart rate, abnormal sweating, indigestion, and urinary and sexual dysfunction

Treatment Methods

1. Fundamental treatment
   • Blood glucose control: Correcting and maintaining long-term hyperglycemia is the most important management method. Individual targets (e.g., the HbA1c target) are adjusted according to the patient’s condition.
2. Pain control (drug therapy) — standard approach
   • First-line recommended medications: Duloxetine, Pregabalin, Gabapentin
   • Alternatives: tricyclic antidepressants (e.g., amitriptyline) — use caution in patients with cardiovascular disease and older adults
   • Topical treatments: lidocaine patches, high-concentration capsaicin patches (for localized pain)
   • Other: careful consideration of opioids for refractory pain (caution regarding long-term prescribing and dependence)
   • Treatment by autonomic symptom: orthostatic hypotension (fluid and salt intake, compression stockings, medication (e.g., midodrine)), symptomatic treatment for gastrointestinal and urinary disorders
   • Medication dosage adjustment and confirmation of contraindications according to kidney and liver function are necessary (e.g., some medications require dosage adjustment or restricted use in reduced kidney function)
3. Nonpharmacological treatment
   • Regular aerobic and strength training (improvement of blood glucose control and circulation)
   • Smoking cessation, avoidance of alcohol, weight management
   • Physical therapy and nerve stimulation (such as transcutaneous electrical nerve stimulation) may be considered
4. Complication management
   • If a foot ulcer develops: evaluation for infection, drainage, and wound care; assessment of blood flow (referral to vascular surgery if revascularization is needed); surgical excision or amputation may be considered in some cases
   • Regular foot examinations and the use of custom shoes and orthoses are recommended
5. Precautions (points to note during self-management)
   • Monitor and report medication side effects (drowsiness, dizziness, arrhythmia, etc.)
   • Medication selection and dosage adjustment are necessary in the presence of kidney or liver dysfunction
   • Visit a medical institution immediately if pain does not improve or if there is a wound, redness, abscess, or warmth in the foot

Checklist Before an Outpatient Visit (Including Example Questions)

Items and information to bring

• A list of currently taken medications (including prescriptions, over-the-counter medications, herbal medicines, and supplements)
• Recent test results: HbA1c, fasting blood glucose, kidney function (creatinine, eGFR), liver function, lipid profile, and a recent electrocardiogram (if available)
• Symptom records: when symptoms began, their progression (gradual/rapid), the location and severity of pain (pain scale 0–10), and whether symptoms worsen at night
• Photos of areas suspected to have wounds or ulcers (if possible)
• Previous nerve conduction studies, autonomic function tests, or foot-related medical records (if available)
• Lifestyle information: smoking, alcohol use, exercise frequency, and foot care (whether walking barefoot, type of shoes)
• Blood glucose records (data from a self-monitoring blood glucose meter)

Items that are helpful to explain to the doctor in advance during the visit (example questions for patients)

• "Please make a brief note of when your symptoms began and how they have changed."
• "Please write down the times when the pain is most severe and the activities that worsen it."
• "Please bring records of your daily checks for wounds, odor, or warmth in your feet."

Examples of General Questions to Ask the Doctor

• "What first-line medication do you recommend to relieve my pain? What effects and side effects should I expect?"
• "To what level should my blood glucose target (HbA1c) be managed? Is there a target appropriate for my age and comorbidities?"
• "What specific daily care methods should I follow to reduce the risk of foot ulcers?"
• "My kidney and liver function are slightly reduced. Which medications can I take, and what precautions should I follow?"

Examples of Condition-Specific Questions

• "My nighttime pain is severe. Which medications or nonpharmacological methods are recommended to help me sleep well?"
• "I have almost no sensation in my feet, so I do not notice wounds easily. What shoes or protective equipment should I use to prevent ulcers, and how often should I have regular foot examinations?"

Note: Each treatment option varies depending on the patient’s overall condition (degree of blood glucose control, kidney and liver function, comorbidities, drug interactions, living environment, etc.). Please consult your treating physician regarding a specific diagnosis and treatment plan.