(HealthDay News) – Corneal nerve fiber length (CNFL), as measured using corneal confocal microscopy (CCM), can be used to reliably rule diabetic sensorimotor polyneuropathy (DSP) in or out, according to research published online Feb. 8 in Diabetes Care.

Ausma Ahmed, of the University of Toronto, and colleagues used CCM to measure corneal nerve fiber length, fiber density, branch density, and tortuosity in 89 patients with type 1 diabetes and 64 healthy patients. This information was compared with each patient’s classification of DSP.

The researchers found that, among the 89 patients with diabetes, 37% had DSP. In these patients, all of the CCM parameters that were measured, except for tortuosity, were lower, compared to both the patients with diabetes but without DSP and the healthy controls. A threshold CNFL of ≤14mm/mm² had a sensitivity of 85% and a specificity of 84% in ruling in DSP. Separate threshold values of CNFL, specifically ≥15.8mm/mm² to rule out DSP and ≤11.5mm/mm² to rule in DSP, had improved sensitivity and specificity. Patients with type 1 diabetes with CNFL values between these thresholds may have incipient nerve injury and may be at risk of future neuropathy.

“In the evaluation of a large cohort of type 1 diabetic subjects consisting of a wide spectrum of neuropathy severity, we found that CCM can be used as a proxy for the clinical and electrophysiological definition of DSP, as defined by consensus criteria using nerve conduction studies,” the authors write.

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