Eleven trials compared metformin with insulin (table 2).31 43 58–66 However, most trials reported supplemental insulin use in the metformin group with the exception of two trials.31 64 The risk of most outcomes, including LGA, macrosomia, NICU admission, neonatal hypoglycaemia, pre-eclampsia, PIH and induction of labour, was lower in those randomised to metformin rather than insulin; instrumental delivery was greater in those randomised to insulin (figure 2C). This evidence concerns the gene INS and Hypoglycemia.