Diabetic neuropathy
- Lesion
Years of high blood sugar damage nerves, starting in the toes; numb feet get injured and ulcerate, and the autonomic nerves fail too.
What it is
Diabetes is the commonest cause of peripheral neuropathy worldwide, and about half of people with long-standing diabetes develop it. The main form is a distal, symmetric, length-dependent sensorimotor polyneuropathy that is mostly axonal, starting in the feet. Autonomic neuropathy affects the heart, gut, bladder and erectile function. Less common are painful lumbosacral radiculoplexus neuropathy (diabetic amyotrophy) and mononeuropathies, including entrapments and cranial nerve palsies. Hyperglycaemia damages nerves through advanced glycation end products, the polyol pathway, oxidative stress, and thickening and hyalinization of endoneurial vessels.
Structure
- Loss of myelinated and unmyelinated axons, more distally; regenerating clusters; some segmental demyelination.
- Endoneurial capillaries and arterioles with thick, PAS-positive, reduplicated basement membranes and hyaline walls.
- Radiculoplexus neuropathy: microvasculitis with perivascular inflammation and ischaemic injury.
- Skin biopsy: reduced epidermal nerve fibre density in small-fibre disease.
Step by step
- Chronic hyperglycaemia glycates proteins and forms advanced glycation end products that bind RAGE and trigger inflammation.
- Aldose reductase turns glucose into sorbitol, depleting NADPH and protective glutathione.
- Oxidative stress and mitochondrial dysfunction injure Schwann cells and axons.
- Thickened endoneurial microvessels reduce blood flow and oxygen to nerves.
- The longest axons fail first: symptoms start in the toes and climb, then reach the fingers.
Clinical notes
- Annual foot exams with a monofilament and vibration testing detect loss of protective sensation.
- Tight glucose control slows progression; foot care and footwear prevent ulcers.
- Painful neuropathy is treated with drugs such as gabapentinoids, duloxetine or tricyclics.
Test yourself
Think of the answer, then tap the question to see it.
What is the most common pattern of diabetic neuropathy?
Distal symmetric sensorimotor polyneuropathy, mainly axonal and length-dependent.
Which microvascular change is seen in diabetic nerves?
Thickening and hyalinization of endoneurial arterioles and capillaries with reduplicated basement membranes.
What is one sign of diabetic autonomic neuropathy?
Orthostatic hypotension, gastroparesis, neurogenic bladder or erectile dysfunction, among others.
How does the polyol pathway harm nerves?
Aldose reductase converts glucose to sorbitol, consuming NADPH and lowering antioxidant defences.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Diabetic Neuropathy | MedlinePlus (MedlinePlus, US National Library of Medicine, 2025); Peripheral Neuropathy | MedlinePlus (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.