Diabetic neuropathy is nerve damage caused by chronic hyperglycaemia and metabolic dysfunction. It affects up to 50% of long-standing diabetics and is a diagnosis of exclusion. 👉 Always rule out other causes (B12 deficiency, alcohol, thyroid disease, uraemia, drugs) as they may be treatable.

🔬 Basic Pathophysiology

Persistent hyperglycaemia → accumulation of sorbitol, oxidative stress, advanced glycation end-products.
Microvascular damage to vasa nervorum → axonal degeneration & demyelination.
Both small fibres (pain, temperature) and large fibres (vibration, proprioception) may be affected.

🛡️ Prevention

🎯 T1DM: Early tight glucose control reduces DSPN & autonomic neuropathy risk.
🎯 T2DM: Optimise glycaemic control – slows but does not fully prevent neuropathy.
⚖️ Lifestyle: weight loss, exercise, metabolic syndrome management in prediabetes/T2DM reduces risk.
🚭 Smoking cessation & alcohol moderation protect peripheral nerves.

🔎 Detection & Screening

📅 Annual screening: at T2DM diagnosis, and 5 yrs after T1DM onset.
👣 10g monofilament – predicts ulcer & amputation risk.
🦶 Clinical exam: pinprick & temperature (small fibre); vibration with 128 Hz tuning fork (large fibre).
🧪 Nerve conduction studies: only if atypical (rapid, asymmetric, predominantly motor).

📚 Types of Diabetic Neuropathy

Type	Clinical Features	Notes / Management
🦶 Distal Symmetric Polyneuropathy (DSPN)	Burning, tingling, numbness, worse at night; “glove & stocking” distribution; loss of vibration/temp sense; foot ulcers.	💊 Amitriptyline → Duloxetine / Gabapentin / Pregabalin. 👟 Daily foot checks & footwear advice. ⚠️ Opiates last resort.
🧠 Autonomic Neuropathy	Postural hypotension, resting tachycardia, gastroparesis, diarrhoea, erectile dysfunction, gustatory sweating, urinary retention.	🫀 Fludrocortisone, Midodrine for OH. 🍽️ Metoclopramide/domperidone for gastroparesis. 🍆 PDE-5 inhibitors for ED. 💩 Codeine phosphate for diarrhoea.
🦵 Proximal Neuropathy (Diabetic Amyotrophy)	Severe thigh/hip pain, progressive quadriceps wasting, unilateral weakness, difficulty rising from chair.	Likely immune-mediated microvasculitis. Tx = analgesia, physio, glucose optimisation. Improves spontaneously over months.
🎯 Focal Neuropathy	Sudden cranial nerve palsy (CN III, IV, VI → diplopia, ptosis), facial nerve palsy, focal limb weakness. Often painful.	Usually self-limiting (weeks–months). Supportive care & exclude compressive lesions.
🌀 Mononeuritis Multiplex	Patchy motor/sensory deficits, can involve cranial nerves.	Self-limiting; rarely steroids/IVIG used in severe cases.

🛠️ Overall Management

🎯 Tight but safe glycaemic control (patient-centred targets in frail/elderly).
💊 Painful neuropathy: first-line = Duloxetine or Pregabalin (NICE). Alternatives = Gabapentin, low-dose TCAs.
🚫 Avoid long-term opioids – dependency risk.
👟 Lifestyle: exercise, weight optimisation, smoking/alcohol reduction.
👣 Foot care: daily inspection, chiropody, protective footwear, podiatry referral if ulcers.

📝 Teaching Pearls

✅ Always check B12, TSH, alcohol use before labelling “diabetic neuropathy”.
👣 Monofilament = cornerstone of foot ulcer prevention (exam favourite!).
⚡ Autonomic neuropathy often under-recognised – always ask about erectile dysfunction, dizziness, gut symptoms.
🧠 Mnemonic: “PA-PF” = Peripheral, Autonomic, Proximal, Focal neuropathies.

📚 References

🎯 Exam Cases

Case 1: 55-year-old man with T2DM presents with burning feet, worse at night. Monofilament testing absent in both feet. 👉 DSPN. Start Duloxetine. Emphasise foot care.

Case 2: 60-year-old woman faints on standing. BP drop 30 mmHg on postural test. 👉 Autonomic neuropathy. Start salt loading, consider Midodrine.

Case 3: 65-year-old with diabetes develops sudden diplopia. Exam: CN VI palsy. 👉 Focal cranial neuropathy. Supportive management, resolves in weeks.

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Diabetic neuropathy