Endocrine Abstracts

The concept of a subclinical form of diabetic peripheral neuropathy (DPN) is well established. Although there has been considerable research of peripheral neuropathy in type 1 diabetes, still there is controversy regarding the pattern of nerve involvement in diabetic neuropathy. Detection of the pattern of nerve involvement can help to establish a protocol for screening of DPN in its subclinical stage.

Aim: The aim of this study was to describe the pattern of nerve involvement in type 1 diabetic patients with subclinical neuropathy using nerve conduction studies (NCS).

Materials and methods: 65 patients with type 1 diabetes (DM1) and 34 controls without diabetes matched to the patient group were included. All patients and controls underwent a standard neurological examination (NSS and NDS (the variant used in Belarus) score) and bilateral NCS of the sensory and motor lower limb nerves using NeuroSoft machine. Interpretation of the results was based on the following normal reference ranges:n. Peroneus superficialis A > 10 µV, v > 45 m/s; n Suralis A > 5 µV, v > 45 m/s; n Peroneus profundus A > 3 mV, v > 40 m/s; n Tibialis A > 3.5 mV, v > 40 m/s.

Results: Clinically evident DPN was detected in 14 diabetic patients from 65 examined. The use of NCS allowed to identify the subclinical stage of polyneuropathy (abnormalities in at least two of the electrophysiological parameters) additionally in 35 patients who had no symptoms and clinical signs of DPN. Regarding abnormal NCS parameters in patients with subclinical diabetic neuropathy, amplitudes reduction for the n. Peroneus superficialis and n. Peroneus profundus predominated. Median of the amplitude for n. Peroneus superficialis in patients with subclinical DPN was 7.22 [5.25; 8.54] µV vs 12.4 [10.57; 16.2] µV in the controls, P < 0.001; for n. Peroneus profundus 2.21 [1.68; 2.68] mV vs 3.15 [3.04; 3.42] mV, P < 0.001. Significant differences in the amplitudes for n. Suralis and n. Tibialis has not been identified. Nerve conduction velocity (NCV) in patients with the subclinical DPN and the control groups was within the reference range. However, the medians of NCV for n. Suralis and n. Tibialis were significantly lower in the group of patients with neuropathy compared with the controls – 47.08 [44.35; 50.13] m/s vs 51.3 [47.6; 59.05] m/s, P = 0.025 and 44.8 [42.15; 48.2] m/s vs 49.35 [48.30; 53.45] m/s, P = 0.004, respectively.

Conclusion: In patients with type 1 diabetes with a subclinical stage of diabetic polyneuropathy the most frequent neurophysiological abnormality was reduced amplitudes (the axonal damage) for sensory and motor fibers of n. Peroneus.