SUDOSCAN for the Early Detection of Diabetic Neuropathy: A Systematic Review of the Diagnostic Performance and Clinical Utility

Background: Diabetic neuropathy (DN) is a common complication of diabetes mellitus that remains frequently undetected by conventional diagnostic methods. Sudomotor dysfunction, reflecting small-fiber impairment, has emerged as a potential early marker. SUDOSCAN, a rapid and non-invasive device measuring electrochemical skin conductance (ESC), has been proposed as a screening tool for early DN. The objective of this study was to systematically evaluate the diagnostic performance and clinical utility of SUDOSCAN in the early detection of DN. Methods: A systematic review was conducted in accordance with the PRISMA 2020 guidelines. Studies assessing SUDOSCAN-derived ESC in adults with diabetes were included. Data on diagnostic accuracy, correlations with established neuropathy measures, and clinical applicability were extracted. Where feasible, pooled sensitivity and specificity were estimated using a random-effects model. Results: Fifteen studies (n = 7343 participants) were included in the qualitative synthesis, with five of them contributing to the quantitative analysis. Reduced ESC values were consistently associated with DN, including early and asymptomatic cases. Pooled sensitivity and specificity for detecting DN were 0.81 (95% CI 0.73–0.87) and 0.73 (95% CI 0.57–0.85), respectively. ESC values correlated with neuropathy severity scores and autonomic dysfunction measures. However, substantial heterogeneity was observed due to variability in diagnostic criteria, ESC thresholds, and study populations. Conclusions: SUDOSCAN is a feasible, rapid, and non-invasive tool for detecting DN, particularly in the early-stage or small-fiber disease. It shows promise as a screening and adjunctive diagnostic modality, especially when combined with established clinical tools. Nevertheless, the lack of standardized thresholds limits its standalone use.