FOXM1 and type 1 diabetes mellitus: Importantly, frequent repeated cycles of ER stress diminished β-cell plasticity, as shown by an inability to recover expression of their identity genes, including Ins1 and Ins2. Laser-captured islets and scRNA-seq data from patients with T1D indicated gene expression alterations in T1D β-cells consistent with a model of ER stress adaptive exhaustion and deregulation of the β-cell ER adaptome during disease progression.