title: Differential reduction in corneal nerve fiber length in patients with type 1 or type 2 diabetes mellitus.
abstract: OBJECTIVE
  To examine the relationship between corneal nerve fiber length (CNFL) and diabetic neuropathy (DN) status in patients with type 1 or type 2 diabetes mellitus (DM).
  
  
  METHODS
  In this cross-sectional study, we examined 25 diabetic patients without DN, 10 patients with mild DN, 8 patients with severe DN, and 9 controls without diabetes. DN status was assigned based on a combination of clinical symptoms, signs, and electrophysiological testing. Patients underwent corneal confocal microscopy (CCM) of the sub-basal nerve plexus. Post-hoc analysis of the CCM images was performed to quantify the average CNFL, and ANOVA was used to assess for differences in CNFL.
  
  
  RESULTS
  All 25 subjects without DN had type 1 DM, and subjects with DN had type 2 DM. Participants with severe DN had significantly lower CNFL (12.5±6.1mm/mm(2)) compared to controls (20.7±2.2mm/mm(2)) (p=0.009). However, lower CNFL was also found in participants with type 1 DM who did not have DN (15.1±4.7mm/mm(2)) relative to controls (p=0.033).
  
  
  CONCLUSIONS
  CCM of the sub-basal nerve plexus may be an indicator of early peripheral nerve degeneration in type 1 DM. Type of diabetes, in addition to degree of neuropathy, may influence the extent of corneal nerve damage.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School.
authors.forename: Maxwell S
authors.initials: MS
authors.lastname: Stem
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School.
authors.forename: Munira
authors.initials: M
authors.lastname: Hussain
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI.
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Lentz
authors.affiliation: University of Michigan Undergraduate Program, Ann Arbor, MI.
authors.forename: Nilesh
authors.initials: N
authors.lastname: Raval
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Gardner
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI.
authors.forename: Rodica
authors.initials: R
authors.lastname: Pop-Busui
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Michigan Medical School. Electronic address: ronim@med.umich.edu.
authors.forename: Roni M
authors.initials: RM
authors.lastname: Shtein
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D048429:Cell Size; D003315:Cornea / Q000294:innervation*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D003929:Diabetic Neuropathies / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D011379:Prognosis; D055815:Young Adult
keywords: Corneal confocal microscopy; Corneal nerves; Diabetes mellitus; Neuropathy; Sub-basal nerve plexus