The diagnostic accuracy of Neuropad for assessing large and small fibre diabetic neuropathy

Diabet Med. 2014 Dec;31(12):1673-80. doi: 10.1111/dme.12536. Epub 2014 Jul 14.


Aims: Neuropad is a simple visual indicator test, with moderate diagnostic performance for diabetic peripheral neuropathy. As it assesses sweating, which is a measure of cholinergic small nerve fibre function, we compared its diagnostic performance against established measures of both large and, more specifically, small fibre damage in patients with diabetes.

Methods: One hundred and twenty-seven participants (89 without diabetic peripheral neuropathy and 38 with) aged 57 ± 9.7 years underwent assessment with Neuropad, large nerve fibre assessments: Neuropathy Disability Score, vibration perception threshold, peroneal motor nerve conduction velocity; small nerve fibre assessments: neuropathy symptoms (Diabetic Neuropathy Symptoms score) corneal nerve fibre length and warm perception threshold.

Results: Neuropad has a high sensitivity but moderate specificity against large fibre neuropathy assessments: Neuropathy Disability Score (> 2) 70% and 50%, vibration perception threshold (> 14 V) 83% and 53%, and peroneal motor nerve conduction velocity (< 42 m/s) 81% and 54%, respectively. However, the diagnostic accuracy of Neuropad was significantly improved against corneal nerve fibre length (< 14 mm/mm2) with a sensitivity and specificity of 83% and 80%, respectively. Furthermore, the area under the curve for corneal nerve fibre length (85%) was significantly greater than with the Neuropathy Disability Score (66%, P = 0.01) and peroneal motor nerve conduction velocity (70%, P = 0.03). For neuropathic symptoms, sensitivity was 78% and specificity was 60%.

Conclusions: The data show the improved diagnostic performance of Neuropad against corneal nerve fibre length. This study underlines the importance of Neuropad as a practical diagnostic test for small fibre neuropathy in patients with diabetes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Diabetes Mellitus, Type 1 / complications
  • Diabetes Mellitus, Type 2 / complications
  • Diabetic Neuropathies / diagnosis*
  • Diabetic Neuropathies / etiology
  • Diabetic Neuropathies / physiopathology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neural Conduction / physiology
  • Perception / physiology
  • Peroneal Nerve / physiopathology
  • Sensitivity and Specificity
  • Sweat Glands / innervation*
  • Sweat Glands / physiopathology
  • Sweating / physiology
  • Vibration