The Diagnostic Utility of VibraTip for Distal Symmetrical Polyneuropathy in Type 2 Diabetes Mellitus

INTRODUCTION: The aim of this study was to assess the performance of VibraTip, a device used to test a person’s vibration perception during routine checks for peripheral neuropathy, against two thresholds of the Neuropathy Disability Score (NDS) for diagnosing distal symmetrical polyneuropathy (DSPN) in patients with type 2 diabetes mellitus (T2DM). METHODS: One hundred consecutive subjects with T2DM were enrolled in the study, of whom 54 were men. The mean age was 62.3 years, and the mean T2DM duration was 12.6 years. VibraTip was used at one foot site (on the pulp of the hallux; protocol A) and at three foot sites (pulp of the hallux and first and third metatarsal head; protocol B). NDS thresholds of ≥ 3 and ≥ 6 were used to establish the diagnosis of DSPN. RESULTS: Against the NDS ≥ 3 threshold, VibraTip showed a very high sensitivity (91.3%) and negative predictive value (NPV) (92%) and a high specificity (85.2%) with protocol A, and a very high sensitivity (95.6%) and NPV (96.1%) and a very high specificity (90.7%) with protocol B. Against the NDS ≥ 6 threshold, VibraTip showed a very high sensitivity (100%) and NPV (100%) and a very high specificity (95.2%) with protocol A, and very high sensitivity (100%) and NPV (100%) and very high specificity (96.8%) with protocol B. CONCLUSIONS: The diagnostic performance of VibraTip is very high in patients with T2DM, rendering it a very useful device as a screening tool, particularly for the exclusion of DSPN. VibraTip performs very well at both NDS thresholds, but particularly well at the NDS ≥ 6 threshold. There appears to be no need to examine sites other than the hallux site with Vibratip.