Relationship between morphological changes of corneal nerve fibers and diabetic cardiac autonomic neuropathy

Abstract

Objective To investigate the relationship between corneal nerve fibers and diabetic cardiac autonomic neuropathy (DCAN), and explore the early diagnosis of DCAN. Methods From September 2017 to March 2018, 62 inpatients with diabetes mellitus [28 males, 34 females, average age (57±13) years] and 20 healthy volunteers [8 males, 12 females, and average age (52±8) years] were enrolled. The Ewing test, 24 h dynamic electrocardiogram, and in vivo corneal confocal microscopy (IVCCM) were performed. According to Ewing test, diabetic patients were divided into DCAN group (n=30) and non-DCAN group (n=32). The differences of corneal nerve parameters between DCAN group, non-DCAN group and normal control group were compared. The correlation between corneal nerve parameters and Ewing test parameters and heart rate variability (HRV) parameters was analyzed. The diagnostic value of corneal nerve parameters for DCAN was evaluated by receiver operating characteristic (ROC) curve. Results Corneal nerve parameters in the DCAN group were significantly lower than those in the non-DCAN group, while those in the non-DCAN group were significantly lower than those in the control group. After adjusting age, duration of disease, glycated hemoglobin A1c and body mass index, corneal nerve parameters were significantly correlated with total Ewing score (r=-0.739--0.576, P=0.000) and deep breathing heart rate difference (r=0.284-0.442, P=0.000~0.013). CNFD was significantly correlated with HRV index (r=0.254-0.450, P=0.000-0.028). The area under the ROC curve of the corneal nerve parameters used to diagnose DCAN ranged from 0.890 to 0.939. The diagnostic sensitivity and specificity of CNFD and CNBD were above 80%. Conclusions The corneal confocal microscopy could promote the early diagnosis of DCAN. IVCCM is a useful supplement to DCAN diagnostic methods. Key words: Diabetic neuropathies; Early diagnosis; Corneal confocal microscopy