The overall objective of the EMERGE trial is to determine if, in women with GDM managed with usual care, the early introduction of metformin vs. placebo reduces (a) the need for insulin use or hyperglycaemia (primary outcome); (b) excessive maternal weight gain; (c) maternal and neonatal morbidities; and (d) cost of treatment. The gene discussed is INS; the disease is Hyperglycemia.