.DELTA.2-trans Eicosenoic acid is an α,β-unsaturated fatty acid that is a bi-product of the synthesis of .DELTA.2-cis eicosenoic acid. .DELTA.2-cis eicosenoic acid and its salts have potential medical use for treating diabetes and improving lipid metabolism. A related compound, 2-octadecenoic acid, has been shown to improve liver function and decrease blood sugar in streptozocin-induced diabetic rats.{13726}