Detecting pain severity with full cup test in painful diabetic peripheral neuropathy

Objectives: The aim of this study was to test the utility and validity of the full cup test (FCT) to assess the severity of pain in subjects with painful diabetic peripheral neuropathy (PDPN). Methods: Subjects with diabetic PDPN were enrolled for this prospective, cross-sectional study. Other causes of PDPN and subjects with cognitive impairment were excluded. The diagnosis of neuropathic pain was made using the results of a physical examination and the Douleur Neuropathique 4 questionnaire. Pain severity was assessed with a FCT and a visual analog scale (VAS) administered before and after treatment. The correlation of FCT with VAS was evaluated to examine validity. Results: A total of 43 (33 female, 10 male) subjects were included. The mean age was 61.9 +/- 8.25 years and the mean disease duration was 13.02 +/- 7.6 years. Type I diabetes mellitus (DM) was present in 2 (4.7%) subjects and Type II DM in 41 (95.3%) subjects. The mean glycated hemoglobin level was 8.9 +/- 1.9 mmol/mol. When the mean VAS and FCT scores were analyzed, the results were 6.7 +/- 2.05 and 66.35 +/- 23.2, respectively, pretreatment and 4.6 +/- 2.2 and 41.36 +/- 23.5 posttreatment, which were both statistically significant (p<0.001, p<0.001). The mean control period was 23.4 days (min-max: 15-30 days). The VAS and FCT scores in pretreatment and posttreatment demonstrated a high positive correlation (r s=0.86, p<0.001; r s=0.843, p<0.001). Conclusion: The FCT can be useful to detect pain severity in PDPN.