Corneal confocal microscopy identifies early and definite diabetic cardiac autonomic neuropathy

Advanced cardiac autonomic neuropathy (CAN) is associated with increased mortality in people with diabetes. Early identification and reduction of risk factors can limit the progression of CAN. However, the diagnosis of early CAN relies on cardiac autonomic reflex testing (CART's) which is not widely available. We have compared the diagnostic utility of corneal confocal microscopy (CCM) to CART's in diagnosing CAN.

Two-hundred and thirty eight individuals with type 1 and type 2 diabetes and thirty seven healthy controls were assessed using CARTs and CCM.

There was a progressive and significant reduction in DB-HRV, E:I ratio, 30:15 ratio, corneal nerve fibre density (CNFD), corneal nerve branch density (CNBD) and corneal nerve fibre length (CNFL) with increasing severity of CAN. The receiver operating characteristic (ROC) area under the curve (AUC) and sensitivity/specificity of CCM were comparable to those of CARTs for identifying early and definite CAN.

CCM is a rapid, non-invasive ophthalmic test which could be used to detect early and established CAN.