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Clinical Trial
. 2017 Jun 13;88(24):2294-2301.
doi: 10.1212/WNL.0000000000004033. Epub 2017 May 17.

Effect of omega-3 Supplementation on Neuropathy in Type 1 Diabetes: A 12-month Pilot Trial

Free PMC article
Clinical Trial

Effect of omega-3 Supplementation on Neuropathy in Type 1 Diabetes: A 12-month Pilot Trial

Evan J H Lewis et al. Neurology. .
Free PMC article


Objective: To test the hypothesis that 12 months of seal oil omega-3 polyunsaturated fatty acids (ω-3 PUFA) supplementation will stop the known progression of diabetic sensorimotor polyneuropathy (DSP) in type 1 diabetes mellitus (T1DM).

Methods: Individuals with T1DM and evidence of DSP as determined by a Toronto Clinical Neuropathy Score ≥1 were recruited to participate in a single-arm, open-label trial of seal oil ω-3 PUFA supplementation (10 mL·d-1; 750 mg eicosapentaenoic acid, 560 mg docosapentaenoic acid, and 1,020 mg docosahexaenoic acid) for 1 year. The primary outcome was the 1-year change in corneal nerve fiber length (CNFL) measured by in vivo corneal confocal microscopy, with sensory and nerve conduction measures as secondary outcomes.

Results: Forty participants (53% female), aged 48 ± 14 years, body mass index 28.1 ± 5.8 with diabetes duration of 27 ± 18 years, were enrolled. At baseline, 23 participants had clinical DSP and 17 did not. Baseline CNFL was 8.3 ± 2.9 mm/mm2 and increased 29% to 10.1 ± 3.7 mm/mm2 (p = 0.002) after 12 months of supplementation. There was no change in nerve conduction or sensory function.

Conclusions: Twelve months of ω-3 supplementation was associated with increase in CNFL in T1DM.

Clinicaltrialsgovidentifier: NCT02034266.

Classification of evidence: This study provides Class IV evidence that for patients with T1DM and evidence of DSP, 12 months of seal oil omega-3 supplementation increases CNFL.


Figure 1
Figure 1. Consort diagram of participants
Figure 2
Figure 2. Change in corneal nerve fiber length (CNFL) during 12 months of omega-3 supplementation
(A) Primary outcome analysis shows change from baseline (p = 0.002). (B) CNFL percent change from baseline. (C) Change in CNFL in participants with and without baseline diabetic sensorimotor polyneuropathy (DSP). Baseline CNFL was higher in the DSP absent subgroup (+, p = 0.01). (D) CNFL change by DSP diagnosis and future DSP risk. The low-risk group was stable at +7%. The high-risk and DSP present groups increased by 56% and 27%, respectively. Analyses were performed using paired Student t tests. All analyses are compared to baseline. Data are shown as mean ± SD (*p < 0.05, **p < 0.01).

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