The Reference Distribution of Annual Change in Corneal Nerve Fibre Length in Diabetes Mellitus

The measurement of corneal nerve fibre length (CNFL) by in vivo corneal confocal microscopy is a biomarker for the presence of diabetic sensorimotor polyneuropathy (DSP). We aimed to determine the reference distribution of annual CNFL change, its prevalence in T1D and T2D, and its clinical predictors. We examined longitudinal data from 94 nondiabetic controls and 297 diabetes participants (224 T1D and 73 T2D) from an ongoing multi-centre NIH-funded study of IVCCM in diabetes. Participants were included if they had at least 1-year of follow-up data and were classified as progressors with “rapid corneal nerve fibre loss” (RCNFL) if the loss of CNFL was beyond the 5th percentile (-14%/y) of the nondiabetic controls. Nondiabetic controls were 43.0±15.8 y, had a median of 2 follow-up visits over a median of 2 y, baseline CNFL of 15.4±4.2 mm/mm2, and the median annual change in CNFL was -1.7%[90% CI, -14.3 to 30.9%]. Diabetes participants were 49.6±15.5 y, had a median of 3 visits over a median of 2 y, baseline CNFL of 14.3±4.4 mm/mm2 and the median annual change in CNFL was 1.8%[90% CI, -26.1 to 25.0%]. There were 33(11.1%) cases of RCNFL in the diabetes sub-cohort, which was comparable between T1D (26(11.6%)) and T2D (7(9.6%)). Progressors did not differ from non-progressors for baseline levels of age, sex, BMI, HbA1c or CNFL levels. However, progressors were more likely to have baseline DSP (16(50%) vs. 83(32%), p=0.048), lower cooling detection threshold (21.3 C±8.5 vs. 25.3 C±7.2, p=0.048) and lower heart rate variability (26.3±13.1 vs. 38.2±25.4, p=0.036). A more rapid loss of CNFL (RCNFL) exceeding 14%/y occurs in ∼11% of diabetes patients. This more rapid of corneal nerves may identify patients at highest risk for the development or progression of DSP. Disclosure E.J.H. Lewis: Employee; Self; Nutarniq Corp. M. Tavakoli: None. L. Lovblom: None. E.M. Halpern: None. M. Jeziorska: None. D. Pacaud: Research Support; Self; Eli Lilly and Company, Novo Nordisk Inc., National Institute of Diabetes and Digestive and Kidney Diseases, Versartis, Inc. N. Pritchard: Other Relationship; Self; JDRF, NHMRC. R.M. Shtein: None. N. Efron: None. V. Bril: Consultant; Self; Alexion Pharmaceuticals, Inc.. Research Support; Self; CSL Behring, Grifols. Advisory Panel; Self; CSL Behring. Consultant; Self; Grifols. Research Support; Self; Shire. Advisory Panel; Self; Pfizer Inc.. R.A. Malik: None. B.A. Perkins: Advisory Panel; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH, Novo Nordisk Inc.. Advisory Panel; Self; Novo Nordisk Inc., Abbott. Speaker's Bureau; Self; Abbott, Janssen Pharmaceuticals, Inc.. Advisory Panel; Self; Insulet Corporation. Speaker's Bureau; Self; Insulet Corporation, Dexcom, Inc..