a Lunenfeld-Tanenbaum Research Institute, Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Canada
b Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada
c Ellen and Martin Prosserman Centre for Neuromuscular Disorders, Division of Neurology, University Health Network, University of Toronto, Toronto, Canada
Omega-3 (n-3) polyunsaturated fatty-acids are essential for the development and maintenance of nerve function, but the relationship of plasma n-3 to the presence of diabetic distal-symmetric-polyneuropathy (DSP) and the effect of n-3 therapy on plasma levels and small nerve fibre morphology in T1D are unknown.
Participants with T1D (n = 40, 53% female, aged (mean ± SD) 48 ± 14 years, BMI 28.1 ± 5.8 kg/m2, diabetes duration 27 ± 18 years), 23 of whom had DSP, took seal-oil (10 mL/day; 750 mg eicosapentaenoic acid (EPA), 560 mg docosapentaenoic acid (DPAn-3), and 1020 mg docosahexaenoic acid (DHA)) for 12-months in a single-arm open-label study. The improvement in corneal nerve fibre length (CNFL) (primary outcome) was previously reported. In this secondary analysis, plasma n-3s were measured at baseline, 4, 8 and 12-months.
At baseline, participants with DSP had lower DHA than those without (1.73 ± 0.89 vs. 2.27 ± 0.70%, p = 0.049). Twelve-months seal-oil therapy increased mean plasma EPA by 185%, DPA by 29%, DHA by 79% (p < 0.001) and CNFL by 29% (p = 0.001). Change in CNFL was positively associated with higher baseline total n-3 (Spearman's correlation coefficient r = 0.41, p = 0.013), DPA (r = 0.33, p = 0.047) and DHA (r = 0.42, p = 0.012).
In conclusion, low plasma DHA was associated with prevalent DSP, n-3 therapy increased blood n-3 levels and higher baseline n-3s were associated with greater nerve regeneration.