INS and type 1 diabetes mellitus: Although two T1DM individuals had δ26Mg values that were 0.27 and 0.30‰ higher following insulin injection/meal consumption, no difference (p = 0.18) was observed overall in the T1DM group between samples taken before (mean δ26Mg = −0.30 ± 0.14‰) and after the meal (mean δ26Mg = −0.25 ± 0.15‰).