Bilateral Symmetry and Side-to-Side Variability of Tibial Nerve Cross-Sectional Area on High-Resolution Ultrasound in Diabetic and Healthy Adults

Abstract Background: High-resolution ultrasound enables quantitative evaluation of peripheral nerve morphology. Although bilateral tibial nerve measurements are routinely obtained, the degree of side-to-side variability in adults with and without diabetes is still not fully defined. Objective: To assess bilateral symmetry of the tibial nerve cross-sectional area (CSA) among diabetic and non-diabetic adults. Methods: This prospective study enrolled 60 participants, including 40 adults with diabetes and 20 non-diabetic controls, the study was performed in collaboration with the Rheumatology, Diabetes and Neurology Clinics from which diabetic patients were recruited. Diabetic participants were evaluated according to their diabetes status and presence or absence of DPN. Right and left measurements were compared using the Wilcoxon signed-rank test, while absolute side-to-side differences were assessed between diabetic and control groups using the Mann–Whitney U test. Results: In controls, mean right and left CSA were 8.60 ± 0.88 and 8.60 ± 0.94 mm², respectively (P=1.000). In diabetic participants, the corresponding values were 11.95 ± 1.63 and 12.00 ± 1.63 mm² (P=0.683). The mean absolute side-to-side difference was 0.50 ± 0.51 mm² in controls and 0.60 ± 0.50 mm² in diabetic participants (P=0.471). Right and left measurements were strongly correlated in both groups Conclusion: Tibial nerve CSA demonstrated marked bilateral symmetry in both diabetic and non-diabetic adults. These results support using a consistently chosen side for group-level research when focal unilateral pathology has been excluded, whereas bilateral evaluation remains suitable for individual clinical assessment.