Statistical interaction was not detectable for SCD1 ratios or individual FAs, except 16:0, which showed an inverse association with T2D at higher Cu levels (HR = 0.83, 95% CI 0.68–1.02) but not at lower levels (HR = 1.05, 95% CI 0.88–1.25) (p-interaction = 0.014). Here, SCD is linked to type 2 diabetes mellitus.