Using in vivo corneal confocal microscopy to identify diabetic sensorimotor polyneuropathy risk profiles in patients with type 1 diabetes

Objective: Diabetic sensorimotor peripheral neuropathy (DSP) is the most prevalent complication in diabetes mellitus. Identifying DSP risk is essential for intervening early in the natural history of the disease. Small nerve fibers are affected earliest in the disease progression and evidence of this damage can be identified using in vivo corneal confocal microscopy (IVCCM). Research design and methods: We applied IVCCM to a cohort of 40 patients with type 1 diabetes to identify their DSP risk profile. We measured standard IVCCM parameters including corneal nerve fiber length (CNFL), and performed nerve conduction studies and quantitative sensory testing. Results: 40 patients (53% female), with a mean age of 48 +/- 14, BMI 28.1 +/- 5.8, and diabetes duration of 27 +/- 18 years were enrolled between March 2014 and June 2015. Mean IVCCM CNFL was 12.0 +/- 5.2 mm/mm2 (normal >= 15 mm/mm(2)). Ten patients (26%) without DSP were identified as being at risk of future DSP with mean CNFL 11.0 +/- 2.1 mm/mm(2). Six patients (15%) were at low risk of future DSP with mean CNFL 19.0 +/- 4.6 mm/mm(2), while 23 (59%) had established DSP with mean CNFL 10.5 +/- 4.5 mm/mm(2). Conclusions: IVCCM can be used successfully to identify the risk profile for DSP in patients with type 1 diabetes. This methodology may prove useful to classify patients for DSP intervention clinical trials.