The calcium-regulated transcription coactivator, Ca2+-responsive transactivator (CREST) was expressed in pancreatic beta-cells. Moreover, CREST expression became significantly increased in pancreatic islets isolated from hyperglycemic Goto-Kakizaki rats compared with normo-glycemic Wistar controls. In addition, culture of beta-cells in the presence of high glucose concentrations also increased CREST expression in vitro. To further investigate the role of this transactivator in the regulation of beta-cell function, we established a stable beta-cell line with inducible CREST expression. Hence, CREST overexpression mimicked the glucotoxic effects on insulin secretion and cell growth in beta-cells. Moreover, high glucose-induced apoptosis was aggravated by upregulation of the transactivator but inhibited when CREST expression was partially silenced by siRNA technology. Further investigation found that upregulation of Bax and downregulation of Bcl2 was indeed induced by its expression, especially under high glucose conditions. In addition, as two causing factors leading to beta-cell apoptosis under diabetic conditions, endoplasmic reticulum stress and high free fatty acid, mimicked the high glucose effects on CREST upregulation and generation of apoptosis in beta-cells, and these effects were specifically offset by the siRNA knockdown of CREST. These results indicated that CREST is implicated in beta-cell apoptosis induced by culture in high glucose and hence that CREST may become a potential pharmacological target for the prevention and treatment of type 2 diabetes mellitus. Journal of Endocrinology (2013) 216, 231-243