The present invention relates generally to a population of cells genetically modified to produce insulin in a glucose responsive manner and uses thereof. More particularly, the present invention relates to a population of cells genetically modified to produce insulin in response to physiologically relevant levels of glucose and uses thereof. The cells of the present invention are useful in a wide variety of applications, in particular in the context of therapeutic and prophylactic regimes directed to the treatment of diabetes and/or the amelioration of symptoms associated with diabetes, based on the transplantation of the cells of the present invention into mammals requiring treatment. Also facilitated is the design of in vitro based screening systems for testing the therapeutic effectiveness and/or toxicity of potential adjunctive treatment regimes.