Abstract: The present disclosure addresses cell type heterogeneity during differentiation of human pluripotent stem cells into islet cells by shifting cell identity from alpha cells to beta cells. More specially, the present disclosure provides a clonal human pluripotent stem cell line that broadly expresses the gene NKX6.1 across cells at the pancreatic progenitor cell stage of in vitro differentiation, which yields fewer alpha cells and more beta cells during directed differentiation to islet cells. The present disclosure further provides a method of improving the yield of insulin-producing cells produced from pluripotent stem cells for transplantation into patients with diabetes.