Biochemical use of neurofilament light polypeptide and vitamin B12 in relation to diabetic polyneuropathy in Danish adolescents with type 1 diabetes: a cross-sectional study.

Background: The aim of this study was to investigate serum Neurofilament Light polypeptide (NfL) as a biomarker for diabetic polyneuropathy (DPN) in adolescents with type 1 diabetes (T1D). Secondarily, to investigate vitamin B12 (B12) deficiency as a cause for DPN in adolescents with T1D.

Methods: Cross-sectional study. Sixty Danish adolescents with T1D (age 15-18 years, diabetes duration >5 years) and 23 age-matched control subjects were included. Based on nerve conduction studies (NCS), intraepidermal nerve fibre density (IENFD) and neurological examination, patients were divided into three groups: (1) T1D without DPN, (2) T1D with subclinical DPN and (3) T1D with confirmed DPN. Blood levels of NfL, B12, B12-binding protein holotranscobalamin (HoloTC) and methylmalonic acid (MMA) were determined.

Results: Twenty-four of the adolescents were without DPN, twenty-one had subclinical DPN and eight had confirmed DPN. NCS was not conducted in three participants and four patients did not have blood samples taken. There were no significant differences in NfL levels or any of the B12 parameters between any of the groups.

Conclusions: NfL used in a cross-sectional manner was not found useful to distinguish between the adolescents with DPN and those without. Vitamin B12 deficiency did not contribute to neuropathy in Danish adolescents with T1D.