Diabetic Neuropathy: The Many Patterns of Nerve Damage

Last updated 17 August 2026.

Key points

Diabetic neuropathy: nerve damage attributable to diabetes once other causes have been excluded. It affects around half of all people with diabetes at some point.
Commonest pattern: distal symmetrical sensorimotor polyneuropathy - a length-dependent glove and stocking loss that starts in the toes and moves proximally.
Screening: annual foot examination with a 10 g monofilament, a 128 Hz tuning fork and ankle reflexes. Loss of protective sensation is what predicts ulceration.
Painful neuropathy: first line is amitriptyline, duloxetine, gabapentin or pregabalin. If one fails, switch to another rather than adding on.
Autonomic neuropathy: postural hypotension, resting tachycardia, gastroparesis, erectile dysfunction, bladder dysfunction and hypoglycaemia unawareness.
Silent myocardial infarction: cardiac autonomic neuropathy blunts anginal pain, so an infarct may present as breathlessness, collapse or nothing at all.
The classic mononeuropathy: a third nerve palsy that spares the pupil, because the ischaemic insult affects central fibres while sparing the peripheral parasympathetic ones.
Always exclude the mimics: particularly vitamin B12 deficiency, which is common in patients on long-term metformin and is treatable.

Introduction

Diabetic neuropathy is the commonest complication of diabetes, affecting around half of all patients during their lifetime. It is also the most heterogeneous - the term covers a group of quite different syndromes united only by their association with chronic hyperglycaemia.

Its importance is disproportionate to how often it is discussed. Loss of protective sensation is the single strongest predictor of foot ulceration, and diabetes remains the commonest cause of non-traumatic lower limb amputation in the UK. Autonomic neuropathy, meanwhile, is associated with a substantially increased mortality that is easy to overlook because its features are so diffuse.

Pathogenesis

Chronic hyperglycaemia damages nerves through several converging mechanisms:

The polyol pathway - excess glucose is reduced by aldose reductase to sorbitol, which accumulates intracellularly, causing osmotic stress and depleting NADPH and myo-inositol
Advanced glycation end products - non-enzymatic glycation of structural proteins impairs axonal transport and damages the vasa nervorum
Oxidative stress - excess reactive oxygen species overwhelm antioxidant defences
Protein kinase C activation - causing microvascular dysfunction and reduced nerve blood flow
Microvascular disease of the vasa nervorum - producing nerve ischaemia, which is the dominant mechanism in the acute mononeuropathies

Longer axons are affected first, because they are most vulnerable to impaired axonal transport - which is why symptoms begin in the toes and ascend, and why the hands are involved only once the legs are affected to the level of the knees.

Distal symmetrical sensorimotor polyneuropathy

This accounts for around 75% of diabetic neuropathy and is what is usually meant by the unqualified term.

Symptoms

Negative (loss of function) symptoms - numbness, deadness, a feeling of walking on cotton wool, and unsteadiness in the dark from loss of proprioception. These are the dangerous ones, because the patient cannot feel injury.
Positive symptoms - burning, shooting or electric pains, paraesthesia, and allodynia where light touch such as bedclothes is painful
Characteristically worse at night, which is a useful discriminator from vascular claudication
Distribution is symmetrical and length-dependent - starting in the toes, ascending the feet and legs, and involving the fingertips only once the sensory level reaches around the knees, producing the glove and stocking pattern
Motor involvement is later and milder - small muscle wasting in the foot causes clawing of the toes and alters weight distribution, generating callus and then ulceration

Examination and screening

Every person with diabetes should have an annual foot check.² The purpose is not to characterise the neuropathy precisely but to identify loss of protective sensation.

The components of neurological foot assessment.
Test	Method and interpretation
10 g monofilament	Applied perpendicular to the skin until it buckles, at several standard sites on the plantar surface, with the patient's eyes closed. Inability to feel it indicates loss of protective sensation and marks the foot as at risk of ulceration.
128 Hz tuning fork	Vibration sense at the hallux and medial malleolus. Often the earliest modality to be lost, since large fibres are affected first.
Ankle reflexes	Symmetrically absent in established neuropathy
Pinprick and temperature	Small fibre function, which may be affected in isolation in early or painful neuropathy with a normal monofilament
Proprioception	Joint position sense at the hallux; loss causes sensory ataxia and a positive Romberg sign
Inspection	Callus, clawing, deformity, dry skin from sudomotor failure, and ulceration - often painless and only found by looking

Other patterns

Autonomic neuropathy

Autonomic neuropathy by system.
System	Features
Cardiovascular	Resting tachycardia, loss of heart rate variability, postural hypotension, exercise intolerance, and silent myocardial ischaemia. Cardiac autonomic neuropathy is independently associated with increased mortality and with sudden death.
Gastrointestinal	Gastroparesis - early satiety, bloating, vomiting of undigested food, and erratic glycaemic control because absorption no longer matches the insulin. Also oesophageal dysmotility, diabetic diarrhoea (often nocturnal and explosive), constipation and faecal incontinence.
Genitourinary	Erectile dysfunction - very common, often the earliest autonomic feature, and rarely volunteered unless asked. Also retrograde ejaculation, female sexual dysfunction, and a neurogenic bladder with incomplete emptying, overflow incontinence and recurrent urinary infection.
Sudomotor	Anhidrosis of the feet - causing dry, cracked skin that predisposes to ulceration - with compensatory truncal sweating, and gustatory sweating on eating
Metabolic	Hypoglycaemia unawareness, from loss of the adrenergic warning response
Pupillary	Reduced pupillary responses and poor dark adaptation

Mononeuropathies

Third cranial nerve palsy - the classic diabetic mononeuropathy. It presents with ptosis, a divergent eye and diplopia, and characteristically spares the pupil. The reason is anatomical: the parasympathetic fibres run peripherally in the nerve and are supplied by pial vessels, while a diabetic microvascular infarct affects the central fibres. A painful third nerve palsy with a dilated pupil is a posterior communicating artery aneurysm until proven otherwise and requires immediate imaging.
Sixth and fourth nerve palsies - also occur, causing diplopia
Median neuropathy at the wrist (carpal tunnel syndrome) - substantially more common in diabetes
Ulnar neuropathy at the elbow, and common peroneal palsy causing foot drop
Most diabetic mononeuropathies are ischaemic, acute in onset and recover spontaneously over 3 to 6 months

Diabetic amyotrophy

Also called proximal diabetic neuropathy or lumbosacral radiculoplexus neuropathy. Typically affects older men with type 2 diabetes, often with relatively good glycaemic control, and presents with severe asymmetrical thigh and hip pain followed by proximal weakness and wasting of the quadriceps, with loss of the knee reflex and marked weight loss. It is frequently mistaken for a lumbar radiculopathy or malignancy. Most patients improve over 6 to 18 months, though recovery may be incomplete.

Truncal radiculopathy and treatment-induced neuropathy

Truncal radiculopathy - a band of pain or dysaesthesia over the chest or abdomen in a dermatomal distribution, which mimics shingles, cardiac or intra-abdominal pathology and prompts a great many negative investigations
Treatment-induced neuropathy of diabetes (insulin neuritis) - an acute, severe painful neuropathy with autonomic features developing within weeks of a rapid improvement in glycaemic control, for example an HbA1c falling by more than 30 mmol/mol in 3 months. It is important to recognise so that improved control is not blamed and abandoned; the pain settles over months.

Excluding the mimics

Diabetic neuropathy is a diagnosis of exclusion, and around 10% of neuropathy in people with diabetes has a different and often treatable cause. Atypical features - rapid onset, asymmetry, predominantly motor involvement, upper limb onset, or severe progression - should prompt a wider search and neurology referral.

Vitamin B12 deficiency - and note that long-term metformin causes B12 malabsorption, so this combination is common, easily missed and readily treated. Check B12 in anyone on metformin with neuropathy.
Alcohol excess and thiamine deficiency
Hypothyroidism
Chronic kidney disease - uraemic neuropathy
Drugs - chemotherapy (platinum agents, vincristine, taxanes), isoniazid, amiodarone, nitrofurantoin, metronidazole and phenytoin
Paraproteinaemia and monoclonal gammopathy - check serum electrophoresis
Vasculitis and connective tissue disease - suspect with mononeuritis multiplex
HIV, hepatitis C, syphilis and leprosy
Hereditary neuropathies - Charcot-Marie-Tooth disease, suggested by pes cavus, a family history and childhood onset
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) - more common in diabetes, and treatable with immunoglobulin or steroids. Suspect with prominent motor involvement, proximal as well as distal weakness and a rapidly progressive course.
Amyloidosis and coeliac disease

A reasonable baseline screen is HbA1c, B12 and folate, thyroid function, U&Es, liver function, full blood count, ESR and serum protein electrophoresis. Nerve conduction studies are not needed for typical distal symmetrical neuropathy but are valuable where the picture is atypical.

Management

Modifying the disease

Optimise glycaemic control - this clearly reduces the development and progression of neuropathy in type 1 diabetes, with a strong effect in the DCCT. The effect in type 2 diabetes is more modest, which is a useful nuance to know.
Address cardiovascular risk factors - hypertension, dyslipidaemia, smoking and obesity all independently contribute to neuropathy progression
Reduce alcohol and correct B12 deficiency
There is no disease-modifying drug for established diabetic neuropathy - treatment is symptomatic and preventive

Neuropathic pain

NICE recommends a defined approach, and the principle that trips people up is that these drugs are used as monotherapy in sequence, not in combination.¹

Offer a choice of amitriptyline, duloxetine, gabapentin or pregabalin as initial treatment
If the first is ineffective or not tolerated, switch to one of the remaining three - and try the others in turn if needed
Tramadol may be used only as rescue therapy for acute exacerbations, not as long-term treatment
Capsaicin cream for localised neuropathic pain in people who wish to avoid or cannot tolerate oral treatment
Refer to a specialist pain service if pain is severe, if it significantly limits function or sleep, or if the underlying condition deteriorates

Practical points on the drugs

Amitriptyline - start at 10 to 25 mg at night and titrate. Anticholinergic effects, sedation, urinary retention and postural hypotension limit its use in older patients; avoid in those with cardiac conduction disease.
Duloxetine - often the preferred first choice in diabetes; nausea is common initially, and it may raise blood pressure
Gabapentin and pregabalin - require dose reduction in renal impairment, which is easily forgotten in a population with diabetic nephropathy. Both cause sedation, dizziness, weight gain and peripheral oedema, and both are now Class C controlled drugs in the UK with recognised misuse potential.
Do not use conventional analgesics such as paracetamol and NSAIDs, which are ineffective for neuropathic pain, or long-term strong opioids outside a specialist setting
Set realistic expectations - a 30 to 50% reduction in pain is a good result, and complete relief is uncommon. Saying this at the outset prevents a cycle of disappointment and escalating prescriptions.

Autonomic neuropathy

Managing the autonomic syndromes.
Problem	Management
Postural hypotension	Review and reduce antihypertensives and diuretics, rise slowly, compression stockings, increase salt and fluid, head-up tilt at night. Fludrocortisone or midodrine if measures fail.
Gastroparesis	Small, frequent, low-fat, low-fibre meals. Metoclopramide (MHRA advice limits use to a maximum of 5 days), domperidone (cardiac risk, short courses) or erythromycin. Adjust insulin timing to match delayed absorption. Consider gastric electrical stimulation in refractory cases.
Diabetic diarrhoea	Loperamide; consider small bowel bacterial overgrowth and treat with antibiotics; exclude coeliac disease and pancreatic exocrine insufficiency
Erectile dysfunction	PDE5 inhibitors first line; address cardiovascular risk, review drugs, check testosterone. Ask about it directly - it is common, treatable and almost never raised by the patient.
Neurogenic bladder	Timed voiding, double voiding, intermittent self-catheterisation; treat and prevent recurrent urinary infection
Gustatory sweating	Topical or systemic antimuscarinics
Hypoglycaemia unawareness	Relax targets to avoid hypoglycaemia for several weeks, and use continuous glucose monitoring with alarms

Foot protection

Annual foot check with risk stratification, and more frequent review for those at moderate or high risk
Education - daily inspection including between the toes, using a mirror if needed, checking water temperature by hand or thermometer before bathing, never walking barefoot, and checking inside shoes before putting them on
Appropriate footwear, and bespoke orthoses or shoes where there is deformity
Podiatry for callus and nail care - patients should not cut their own calluses
Prompt referral of any new ulcer, colour change, swelling or unexplained pain to the multidisciplinary foot service

Complications

Foot ulceration - the principal consequence, arising from unnoticed trauma on an insensate foot
Charcot neuroarthropathy - progressive destruction of the bones and joints of an insensate, well-perfused foot, producing gross deformity and a rocker-bottom sole. Presents as a hot, red, swollen foot, frequently misdiagnosed as cellulitis or gout.
Amputation - diabetes is the leading cause of non-traumatic lower limb amputation in the UK
Falls and fractures - from sensory ataxia, foot deformity and postural hypotension
Silent myocardial infarction and sudden cardiac death
Aspiration and malnutrition from gastroparesis
Erratic glycaemic control - gastroparesis in particular makes insulin timing unpredictable
Recurrent urinary tract infection and renal impairment from an atonic bladder
Chronic pain, sleep disturbance, depression and reduced quality of life - the burden of painful neuropathy is consistently under-recognised
Loss of independence and employment

Red flags

Recognise and act

A hot, red, swollen foot in a patient with neuropathy - Charcot neuroarthropathy until proven otherwise. Offload immediately in a total contact cast and refer to the multidisciplinary foot service the same day; treating it as cellulitis and waiting costs the foot.
Any new foot ulcer - same-day referral to the diabetic foot service
A painful third nerve palsy with a dilated pupil - a posterior communicating artery aneurysm, not diabetes; urgent imaging
Rapidly progressive, asymmetrical or predominantly motor neuropathy - consider CIDP, vasculitis or malignancy, and refer to neurology
Neuropathy in a patient on long-term metformin - check vitamin B12; this is common and reversible
Breathlessness, collapse or unexplained deterioration in a patient with autonomic neuropathy - consider silent myocardial infarction; take an ECG and troponin
Severe postural hypotension - review antihypertensives before adding fludrocortisone, and consider adrenal insufficiency
Vomiting undigested food with erratic glucose control - gastroparesis; adjust insulin timing as well as treating the symptom
Acute severe painful neuropathy after a rapid fall in HbA1c - treatment-induced neuropathy; reassure and treat the pain rather than loosening control
Neuropathic symptoms in the hands before the feet - this is not the pattern of diabetic neuropathy; look elsewhere

Prognosis

Established diabetic neuropathy is largely irreversible, and the realistic aims are to slow progression, control symptoms and prevent the foot complications that follow. Nerve damage progresses in parallel with the duration of diabetes and the quality of glycaemic control, and by 25 years around half of patients are affected.

Some patterns behave much better than the general picture suggests. Mononeuropathies, including third nerve palsies, usually recover spontaneously within 3 to 6 months. Diabetic amyotrophy improves over 6 to 18 months in most patients. Treatment-induced neuropathy resolves over months. Recognising these carries real value, because the prognosis you give determines whether the patient endures the episode or abandons treatment.

Cardiac autonomic neuropathy is the pattern with the worst prognostic implications, being independently associated with increased cardiovascular and all-cause mortality - a fact that argues for looking for it actively rather than treating autonomic symptoms as a nuisance.

The most consequential message is preventive. Loss of protective sensation is the gateway to ulceration, infection and amputation, and the interventions that interrupt that pathway - an annual foot check that actually happens, patient education, podiatry, appropriate footwear and same-day referral of a new ulcer - are low-technology, cheap and consistently under-delivered. Around 80% of diabetes-related amputations are preceded by a foot ulcer, and most of those ulcers were preventable.

References

NICE CG173. Neuropathic pain in adults: pharmacological management in non-specialist settings. 2013, updated 2020. Available here
NICE NG19. Diabetic foot problems: prevention and management. 2015, updated 2019. Available here
NICE NG28. Type 2 diabetes in adults: management. 2015, updated 2022. Available here
NICE NG17. Type 1 diabetes in adults: diagnosis and management. 2015, updated 2022. Available here
NICE Clinical Knowledge Summaries. Diabetes - type 2: neuropathic pain and autonomic neuropathy. Available here
Pop-Busui R, Boulton AJM, Feldman EL et al. Diabetic neuropathy: a position statement by the American Diabetes Association. Diabetes Care. 2017. Available here
MHRA Drug Safety Update. Metoclopramide: risk of neurological adverse effects - restricted duration of use. Available here
BNF. Amitriptyline, duloxetine, gabapentin and pregabalin - neuropathic pain. Available here

This article is written for revision and education. It is not clinical guidance and must not be used to make decisions about the care of a patient. Always check current NICE guidance and local protocols.