Dispersed human islet cells were analyzed for β cell death by insulin-TUNEL costaining (Fig. 9A), after 24 hours of culture in control media containing 10% FCS, or in media in which the FCS was substituted with 10% human serum, either from consented adult T1D subjects with disease diagnosis duration of 1 to 5 years or from ND control subjects best-matched for sex, age, and ethnicity (table S2). Here, INS is linked to type 1 diabetes mellitus.