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Diagnosis of diabetic neuropathy
Medical expert of the article
Last reviewed: 06.07.2025
The diagnosis of diabetic neuropathy is made on the basis of relevant complaints, a history of type 1 or type 2 diabetes mellitus, data from a standardized clinical examination and instrumental research methods (including quantitative sensory, electrophysiological (electromyography) and autofunctional tests).
Complaints and standardized clinical examination
To quantitatively assess the intensity of pain, special scales are used (TSS - General Symptom Scale, VAS - Visual Analogue Scale, McGill scale, HPAL - Hamburg Pain Questionnaire).
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Instrumental research methods
The great importance of methods for studying sensitivity disorders is that they allow diagnosing diabetic neuropathy even before clinical manifestations appear. The disadvantage of all the studies listed below is their non-specificity: the disorders mentioned are possible with neuropathies not associated with diabetes mellitus.
Evaluation of vibration sensitivity. Conducted with a graduated Riedel-Seifert tuning fork with a vibration frequency of 128 Hz on the tip of the big toes of both feet three times, with calculation of the average value (normally > 6 conventional units out of 8).
Assessment of tactile sensitivity. Use a Sernmes-Weinstein monofilament with a force of 1, 2, 5, 10 g. The monofilament is touched perpendicularly to the skin surface for 1.5 seconds with pressure sufficient for the monofilament to bend. The patient's lack of touch sensation indicates a violation of tactile sensitivity.
Assessment of pain sensitivity. Light pricks are applied with a blunt needle. The test is considered positive if the patient experiences pain.
Temperature sensitivity assessment. This is done using the Tip-Therm device. The metal and plastic ends of the device are touched to the patient's skin alternately. The test is considered positive if the patient feels a difference in the temperature of the device's surface.
Electromyography. This method allows to evaluate the condition of peripheral nerves of the motor and sensory nerves of the upper and lower extremities. During stimulation neuromyography, such parameters as the amplitude of the M-response, the speed of excitation propagation, residual latency are studied, allowing to evaluate the severity of neuropathy. Allows to diagnose diabetic neuropathy at an early stage.
Autonomic function tests. Cardiovascular tests are most often used to diagnose diabetic autonomic neuropathy, in particular:
- quantitative determination of heart rate variability during deep breathing (normally the difference between the heart rate during inhalation and exhalation is > 10 beats/min);
- orthostatic test (measurements in the supine position and after standing up). In case of sympathetic innervation disorder, systolic blood pressure decreases to a greater extent than in healthy people. The patient lies quietly on his back for 10 minutes, after which blood pressure is measured. Then the patient gets up, and blood pressure is measured at the 2nd, 4th, 6th, 8th and 10th minutes. A drop in systolic pressure > 30 mm Hg is considered pathological and indicates autonomic cardiac neuropathy with sympathetic innervation disorder;
- Measuring blood pressure under isotonic muscle load. After determining the initial blood pressure, the patient is asked to squeeze a hand dynamometer to 1/2 the maximum strength of the hand for 5 minutes. If the diastolic pressure increases < 10 mm Hg, this indicates autonomic neuropathy with sympathetic innervation damage;
- ECG during Valsalva maneuver. Normally, with an increase in intrapulmonary pressure (straining), the heart rate increases. With a violation of parasympathetic regulation of the heart rate, this phenomenon disappears. The smallest and largest RR intervals are determined on the ECG. The ratio of the maximum RR to the minimum < 1.2 indicates autonomic neuropathy.
Additional methods for diagnosing autonomic diabetic neuropathy include 24-hour Holter ECG monitoring and 24-hour blood pressure monitoring, gastric X-ray with and without contrast, ultrasound of the abdominal organs, intravenous urography, cystoscopy, etc.
Differential diagnosis of diabetic neuropathy
Diabetic neuropathy should be differentiated from neuropathies of other genesis, including alcoholic neuropathy, neuropathy due to taking neurotoxic drugs (nitrofurans, barbiturates, cytostatics, etc.) or exposure to chemicals (some solvents, heavy metals, insecticides), neuropathy within the framework of paraneoplastic syndrome or malabsorption syndrome, nodular periarteritis. In this case, a detailed anamnesis plays a major role.
In the clinical picture, manifestations of autonomic diabetic neuropathy come to the fore. The diagnosis of dysfunction of a particular organ or system as a result of autonomic neuropathy is a diagnosis of exclusion.
In patients with type 2 diabetes mellitus and diabetic radioplexopathy, which may involve bilateral progressive chest pain with spontaneous resolution, the possibility of heart and abdominal diseases must be considered.