Abstract: The present invention in general relates to a method for identifying compounds that influence beta cell number and/or phenotype, more in particular beta cell differentiation, proliferation and/or expansion. Said method comprising culturing beta cells or precursors thereof in 5 medium comprising glucose, and determining the ability of said compound to induce the glucocorticoid receptor dependent-transactivation pathway in said beta cells. It further relates to compounds identified in such methods, and uses of said compounds as positive controls in methods for identifying compounds that influence beta cell number and/or phenotype; or uses thereof in the treatment of pathologies characterized by changes in beta-cell number and/or 10 phenotype such as for example diabetes mellitus.