Take the vials, pens & needles out of the pouch & put into the plastic bag (or have them in a plastic bag in the pouch), declare them to security. They will then put them in a little plastic tray through the xray, collect at the end.
Despite some of their failings they seem to know what the stuff is and I have never had any problems.
Don't forget that the cool blocks (if frozen liquids count as well), useful also to carry a doctor's letter just in case and the the packaging they came in - this in case it is lost or stolen as the makes we get in the UK may not be available abroad, thought the type will be.. Though in 12 years I've only been asked to see it once.
On a long flight have spare plastic bags in case you need to keep the pouch temp down, cabin crew will supply ice (if they have it) but may not have the bags
You may need also to declare the needles to the airline check their web site as all of them cover the requirements for diabetics.
Never ever carry the above in hold luggage!