Diabetes is the leading cause of peripheral neuropathy in industrialised countries. After several years of progression, the prevalence of diabetic peripheral neuropathy affects approximately one third of patients, compared to 6% at the time of diabetes diagnosis—an involvement that is often silent in its early stages. Appropriate screening and neurological assessment allow for the early identification of this complication, evaluation of its severity, and prevention of its consequences, particularly the risk of foot ulcers. The IENA Neurophysiology centre offers a comprehensive assessment combining EMG and Sudoscan, two complementary tests to investigate all nerve fibres.
What is diabetic neuropathy?
Diabetic neuropathy refers to all disorders of the peripheral nervous system associated with chronic hyperglycaemia. Prolonged glycemic imbalance progressively damages nerves, particularly the longest ones, which explains why symptoms most frequently begin in the feet before gradually spreading up the legs and then to the hands, in a classic "stocking and glove" distribution.
There are several forms of diabetic neuropathy, the most common being distal symmetric sensory-motor polyneuropathy, which affects both large fibres (sensitivity to touch, vibration, muscle strength) and small fibres (sensitivity to pain and temperature, autonomic nervous system function).
Which warning signs should prompt consultation?
In diabetic patients, certain symptoms should raise suspicion of neuropathy and prompt a neurological assessment:
Tingling, numbness, or burning sensations in the feet, often worse at night.
Loss of sensation, with a feeling of "walking on cotton wool".
Neuropathic pain, presenting as electric shocks or sharp pricking sensations.
Reduced perception of pain or heat, leading to an increased risk of injuries going unnoticed.
Balance disorders or instability when walking.
Signs of autonomic nervous system involvement: sweating disorders, orthostatic hypotension, digestive or urinary issues.
The insidious nature of diabetic neuropathy justifies regular screening, even in the absence of suggestive symptoms, particularly for patients with long-standing or poorly controlled diabetes.
Why undergo a specialised neurological assessment?
Clinical examination and the monofilament test, performed during a general medicine or diabetology consultation, allow for initial screening. However, a specialised neurophysiological assessment provides essential additional information:
Objectively confirming peripheral nerve damage, beyond clinical examination alone.
Distinguishing between damage to large nerve fibres and small nerve fibres, which are not investigated by the same tests.
Evaluating the severity and progression of the neuropathy, which is valuable for monitoring.
Ruling out other associated causes of neuropathy (nutritional deficiency, toxic, thyroid dysfunction, hereditary), especially when the clinical presentation is atypical or rapidly progressive.
Guiding therapeutic management and podiatric care.
EMG in diabetic neuropathy
The electromyogram (EMG) is the gold standard test for assessing large myelinated nerve fibres. It allows clinicians to:
Measure motor and sensory nerve conduction velocities, as well as response amplitudes, in both the lower and upper limbs.
Confirm the diffuse, symmetrical, and length-dependent nature of the nerve involvement, which is typical of diabetic neuropathy.
Check for associated conditions, such as carpal tunnel syndrome, which is more common in diabetic patients.
Objectively quantify the severity of the neuropathy, serving as a baseline reference for long-term monitoring.
However, EMG remains of limited sensitivity for assessing small nerve fibres, which are often affected early in diabetes, even before detectable abnormalities appear on an EMG.
The Sudoscan, for assessing small fibres
The Sudoscan is a rapid, non-invasive, and painless test that measures the sweat gland function of small nerve fibres via the electrochemical skin conductance of the hands and feet. It is of particular interest in the evaluation of diabetic neuropathy:
It can detect signs of small fibre damage at a stage when the EMG may still be normal.
The test takes only a few minutes, involves no needles and is completely painless, making it a well-tolerated screening tool, even when repeated for monitoring.
It helps assess the risk of complications, particularly diabetic foot complications, related to autonomic nervous system damage.
Why combine EMG and Sudoscan?
EMG and Sudoscan assess two different and complementary populations of nerve fibres: large myelinated fibres for the EMG, and small unmyelinated fibres for the Sudoscan. Performed during the same consultation, these two tests enable:
A comprehensive neurological assessment of diabetic neuropathy, covering the entire spectrum of affected nerve fibres.
Earlier detection, as the Sudoscan can reveal small fibre damage before the EMG shows abnormal results.
Saved time for the patient, with a single appointment for a complete neurophysiological investigation.
A single, synthesised report, facilitating interpretation for the referring general practitioner or diabetologist.
This combined approach, offered at the IENA Neurophysiology centre, is part of a comprehensive management plan for the diabetic patient, in coordination with the referring doctor, diabetologist, and, if necessary, the podiatrist.
How is the consultation conducted at IENA Neurophysiology?
The IENA Neurophysiology centre, located in the 16th arrondissement of Paris near Trocadéro, offers rapid and coordinated care for diabetic patients referred by their general practitioner or diabetologist:
Prompt appointment booking upon medical referral.
A targeted medical interview and clinical neurological examination.
Both EMG and Sudoscan performed during the same consultation.
A detailed report provided immediately, and sent to the referring doctor and/or diabetologist.
In summary
Diabetes is the leading cause of peripheral neuropathy, affecting approximately one third of diabetic patients.
Symptoms usually begin in the feet but can remain silent for a long time.
EMG assesses large nerve fibres and objectively confirms peripheral nerve damage.
Sudoscan checks for signs of small fibre damage, which can occur earlier, in a quick and painless manner.
Combining EMG and Sudoscan provides a complete neurological assessment in a single consultation.
Early diagnosis helps prevent complications, particularly those relating to the diabetic foot.
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