Early diagnosis of peripheral neuropathy by corneal confocal microscopy in patients with impaired glucose tolerance

Abstract

Objective To investigate the relationship between alterations in the corneal innervation observed by laser confocal microscopy and peripheral neuropathy severity in the patients with impaired glucose tolerance (IGT). Methods A total of 70 patients with IGT were consecutively enrolled into the study.Among them，30 patients were diagnosed as peripheral neuropathy (IGTPN)，40 patients without peripheral neuropathy (IGT-NPN).Fifty age-matched healthy subjects were also studied.Corneal subbasal nerves were investigated by laser confocal microscopy. Results Corneal nerve fiber length (17.1±4.9) vs (14.0±3.8) mm/mm2; t=13.484，P<0.05)，nerve branch density ((53.1±18.8) vs (36.2±11.5) mm/mm2; t=9.369，P<0.01) and nerve fibre tortuosity ((2.07±0.76) vs (0.88±0.55) levels，t=12.957，P<0.05) were significantly increased in IGT-NPN group when compared with control group，but nerve fibre density had no difference.Nerve fiber length，nerve branch density and nerve fibre density were significantly decreased in IGTPN group compared with control group and IGT-NPN group，while NFT was significantly increased in IGT-PN group. Conclusions Patients with impaired glucose metabolism show alterations in corneal innervations before diagnosed with diabetes mellitus or peripheral neuropathy.It indicates that corneal confocal microscopy can be used for early diagnosis of diabetic peripheral neuropathy. Key words: Glucose intolerance; Peripheral nervous system diseases; Cornea; Microscopy，confocal; Early diagnosis