Increased C-reactive protein is associated with corneal nerve loss and painful neuropathic symptoms in Type 2 diabetes mellitus.

AIMS/

INTRODUCTION

To investigate the association between C-reactive protein (CRP) with sensory symptoms and deficits and measures of small fiber damage.

MATERIALS AND

METHODS

Adults with and without T2D underwent corneal confocal microscopy (CCM) and assessment of vibration perception threshold (VPT), DN4 symptom questionnaire, and fasting blood tests for CRP and metabolic markers.

RESULTS

Of the 122 participants, 77 had T2D of whom 23 (29.9%) had DPN, and 45 were controls. CRP levels were significantly higher in those with T2D without and with DPN compared to controls (5.6 ± 2.9 and 5.4 ± 4.0 vs 3.8 ± 2.9 mg/L, P = 0.008 and P = 0.046, respectively), with no difference between those with and without DPN (P = 0.894). Higher CRP was independently associated with lower corneal nerve fiber density (CNFD) (β = -5.5 fibers/mm2 per 10 mg/L increase, P = 0.036), after adjusting for diabetes duration, BMI, HbA1c, and triglycerides. In the DPN group, those with positive symptoms (burning, painful cold, and electric shocks) had higher CRP levels compared to those with negative symptoms (6.5 ± 4.7 vs 3.8 ± 1.9 mg/L, P = 0.039).

CONCLUSIONS

Elevated CRP is associated with small nerve fiber loss and positive neuropathic symptoms in T2D. These findings suggest that CRP may help identify individuals with inflammation-driven DPN who could benefit from targeted interventions.