Metformin and breastfeeding

Just Me • Have a 4 year old daughter and a Newborn GLOW baby girl born 22/04/15..so in love 💕
So I was told a week ago I had gestational diabetes and was told to check my blood levels for a week and then go back to a consultant and see what he thinks the best treatment for me is. Well today was that appt and he decided looking at my glucose levels for the week that I need to go on metformin 500mg 3x a day. Now I'm happy to take them if it means my baby and I are going to be less at risk from the effects of diabetes but I was reading the leaflet that comes with the tablets and it says dont take if breastfeeding or planning to. Well I am planning to. I really want to breastfeed my baby so does this mean these tablets are going to stop be from being able to do so? 
Any info greatly appreciated. I will be asking consultant when I see him next but would like some info in advance.