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Journal of Diabetes Research
Volume 2016, Article ID 3653459, 9 pages
Research Article

The Expanded Bead Size of Corneal C-Nerve Fibers Visualized by Corneal Confocal Microscopy Is Associated with Slow Conduction Velocity of the Peripheral Nerves in Patients with Type 2 Diabetes Mellitus

1Ishibashi Clinic, 1-9-41-2 Kushido, Hatsukaichi, Hiroshima 738-0033, Japan
2Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
3University of Exeter Medical School, St Luke’s Campus, South Cloisters, Exeter EX1 2LU, UK

Received 24 April 2016; Revised 9 June 2016; Accepted 19 June 2016

Academic Editor: Mark A. Yorek

Copyright © 2016 Fukashi Ishibashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study aims to establish the corneal nerve fiber (CNF) morphological alterations in a large cohort of type 2 diabetic patients and to investigate the association between the bead size, a novel parameter representing composite of accumulated mitochondria, glycogen particles, and vesicles in CNF, and the neurophysiological dysfunctions of the peripheral nerves. 162 type 2 diabetic patients and 45 healthy control subjects were studied in detail with a battery of clinical and neurological examinations and corneal confocal microscopy. Compared with controls, patients had abnormal CNF parameters. In particular the patients had reduced density and length of CNF and beading frequency and increased bead size. Alterations in CNF parameters were significant even in patients without neuropathy. The HbA1c levels were tightly associated with the bead size, which was inversely related to the motor and sensory nerve conduction velocity (NCV) and to the distal latency period of the median nerve positively. The CNF density and length positively correlated with the NCV and amplitude. The hyperglycemia-induced expansion of beads in CNF might be a predictor of slow NCV in peripheral nerves in type 2 diabetic patients.