I got really annoyed at heathrow a couple of years ago, they had no problem with the diabetes items but took away the juice box I was carrying for lows, however I had travelled from Boston and was getting a connecting flight and Logan hadn't had a problem with me carrying the juice, and the fact that the queue was so long at security, they then took it away and we had to run to the gate and lo and behold I knew I was going low as we were sat on the bus out to the plane (had a baby and a toddler in tow) so I managed to get onto the plane and managed to get some juice from a flight attendant while digging through bags looking for the glucose tabs that I was carrying as well but which don't work fast for me. I was really annoyed and wished I had complained more at the time.