Diagnostic utility of corneal confocal microscopy in type 2 diabetic peripheral neuropathy

Abstract

Aims/Introduction: The early pathological changes of diabetic peripheral neuropathy (DPN) are mainly small nerve fiber injuries. Corneal confocal microscopy (CCM) is an easy, rapid, non-invasive and repeatable technique to detect the damage of small nerve fibers. The purpose of this study was to explore the application of CCM in DPN and other chronic complications of type 2 diabetes mellitus. Materials and Methods: A total of 220 individuals (48 normal healthy control participants and 172 patients with type 2 diabetes mellitus) were included in the study. All participants were assessed and scored for neurological symptoms and neurological deficits, quantitative sensory test, neuroelectrophysiological test, and CCM. Results: Corneal nerve fiber density, corneal nerve fiber length and corneal nerve branch density were significantly reduced in patients with type 2 diabetes mellitus compared with normal healthy control subjects (P < 0.001, P < 0.001 and P < 0.001, respectively). In the DPN group, corneal nerve fiber density, corneal nerve branch density and corneal nerve fiber length were significantly lower than for patients without DPN (P < 0.001, P < 0.001 and P < 0.001, respectively). Receiver operating characteristic analysis showed that the optimal cutoff values were 24.68, 39 and 15.315, respectively, in which corneal nerve fiber density and corneal nerve fiber length had moderate sensitivity and specificity. Conclusion: This study provides more support for the clinical use of CCM to diagnose type 2 diabetes mellitus-related complications, especially DPN.

Implementation of corneal confocal microscopy for screening and early detection of diabetic neuropathy in primary care alongside retinopathy screening: Results from a feasibility study

“…There were some limitations to this study: first, there was no available information regarding height, triglyceride levels or HbA1c levels, which were previously associated with increased risk of neuropathy (44). A recent study by Wang et al (2020) (45) found that subjects with type 2 diabetes and DPN had significantly higher levels of HbA1c (p=0.035), high-density lipoprotein (p=0.003) and fasting blood glucose (p=0.026). We are unable to confidently conclude that any significant/nonsignificant changes between subgroups of subjects were down to the grouping factor and no other independent factors.…”

“…A recent study by Wang et al. (2020) ( 45 ) found that subjects with type 2 diabetes and DPN had significantly higher levels of HbA1c (p=0.035), high-density lipoprotein (p=0.003) and fasting blood glucose (p=0.026). We are unable to confidently conclude that any significant/non-significant changes between subgroups of subjects were down to the grouping factor and no other independent factors.…”

Artificial Intelligence and Corneal Confocal Microscopy: The Start of a Beautiful Relationship

“…A multicentre, multinational NIH consortium study of 998 participants with type 1 and type 2 diabetes reported that CNFL had a 0.88 sensitivity and 0.88 specificity for the diagnosis of DPN [ 42 ]. A recent study ( n = 220) using a higher optimal threshold than the consortia paper (CNFL < 15.3 mm/mm 2 ) reported 0.8/0.59 sensitivity/specificity for diagnosing DPN [ 43 ]. CNFL predicts incident neuropathy over 4 years [ 25 , 26 ], thus providing a putative ‘at-risk’ threshold.…”

Diabetes Distal Peripheral Neuropathy: Subtypes and Diagnostic and Screening Technologies

“…However, sensitivies and specifities for CCM parameters tended to be highly variable and not uniformly adequate across studies. [72][73][74][75][76][77][78][95][96][97][98]103,[110][111][112][116][117] Beginning evidence suggests CCM and IENFD may have roughly comparable performance in detecting DSPN although additional research is warranted. 72,96 Further, the current longitudinal literature suggests CCM may predict incident DSPN, identify patients at high-risk for DSPN, and monitor progressive nerve damage over time.…”