Hi guys, Nazia here! I have serached for this question on the net and different websites are giving me different answers. I understand that everyone injects different amounts of insulin per day BUT what is the highest amount of insulin somone can inject before it becomes dangerous. Also, for people that use insulin pens, how many mls of insulin does it usually hold? I am doing doing a business proposal and am thinking about redesigning insulin pens to make the needle part "painless". And have got suggestions from diabetic people of somehow making them smaller as well. I need to know how much insulin these pens hold so that i can figure out what size to make mine. Also, what does it mean by units? How does units differ from mls? Thank you for your responses.