Arg34Lys26(Nɛ-(γ-L-glutamyl(Nα-palmitoyl)))-GLP-1(7-37) (NN2211) is currently in development as a diabetes type 2 drug. The fatty acid attached to the GLP-1(7-37) ensures a long and controlled duration of action. The synthesis of [125I]NN2211, [127I]NN2211 and [14C]NN2211 used for preclinical ADME studies are described. NN2211 was iodinated using the lactoperoxidase/hydrogen peroxide method, and [14C]NN2211 was synthesized in 4 steps by two routes both starting from an α-protected [U-14C]glutamic acid. Copyright © 2003 John Wiley & Sons, Ltd.