To explore the impact of FXR on β-cells apoptosis in T2DM, we initially assessed its expression levels and found a significant reduction: ~70% (p < 0.01), ~80% (p < 0.01) and ~70% (p < 0.01) in islets from GK rats, db/db mice and high-fat-diet-induced diabetic mice, respectively, compared to the Wistar rats, C57 mice and normal diet mice (Fig. 6A–C; Supplementary Fig. S6A). The gene discussed is NR1H4; the disease is type 2 diabetes mellitus.