He He K K Guo Guo Q Q Ge Ge J J The efficacy and safety of metformin alone or as an add-on therapy to insulin in pregnancy with GDM or T2DM: a systematic review and meta-analysis of 21 randomized controlled trials The efficacy and safety of metformin alone or as an add-on therapy to insulin in pregnancy with GDM or T2DM: a systematic review and meta-analysis of 21 randomized controlled trials J Clin Pharm Ther J Clin Pharm Ther 2022 2022 47 47 2 2 168 168 177 177 10.1111/jcpt.13503 10.1111/jcpt.13503 supplied-pmid 34363237? This evidence concerns the gene INS and gestational diabetes.