A population of enteroendocrine cells (EEC) is obtained from a mammalian post-natal cell population, such as a population including post-natal stem cells, by treating the population with a plurality of small molecules that upregulate ChgA and promote differentiation of the cells to form the enteroendocrine cells. The upregulation of ChgA is such that the fraction of cells expressing CGA in the obtained cell population, as measured by a ChgA Immunostaining Assay, is at least about 1.5%. Small molecules that can be used to differentiate the post-natal cells into the enteroendocrine cells can include at least one of a Wnt activator, a Notch inhibitor, a Wnt inhibitor, a MEK/ERK inhibitor, a growth factor, a HDAC inhibitor, a Histone Methylation Inhibitor, a Tgf-β inhibitor, and a NeuroD1 activator. Also, the insulin expression of a population of mammalian cells is increased by treating the population with a plurality of small molecules that increase the insulin expression.