INS and type 2 diabetes mellitus: Metformin as first line therapy for T2DM is recommended to be continued after initiating insulin (usually basal insulin (BI)) by current guidelines [8–10] since the regimen of insulin plus concomitant metformin was shown to improve glycemic control, reduce hypoglycemia incidence and weight gain as well as total insulin dose when compared with insulin monotherapy [11–14].