I flew out of Merida on Aviacsa to Mexico City and, after a couple of days, out of Mexico City to Dallas on AA in 2008. As far as I can recall the security process was almost identical to flying out of equivalent US airports. Merida was small and relaxed, Mexico City large and frantic but otherwise no different.
I agree with the other responses about carrying a doctor's letter. Mine has only been needed a couple of times - oddly, on that trip, when I flew out of Dallas - but it saved a lot of hassle on those rare occasiopns when I needed it. Mine is in English. The only time I carried a translation was for my Yellow Fever inoculation waiver in Portuguese for Brazil.
I wrote a few general tips based on my travels here: Travelling With Type 2
Cheers, Alan, T2, Australia
Everything in Moderation - Except laughter
I only have had problems one time, that was flying out or Monterrey, Mexico on VivaAerobus. A lady checking people boarding the flight looked through my diabetic case with all of my insulin and syringes and told me I was only allowed 4 syringes and I had probably 25. I immediately forgot every word of Spanish that I knew when I started trying to tell her I was diabetic and took 4 or 5 shots a day and I needed that supply. A kind bi-lingual older gentleman behind me started helping me argue my case and she finally relented.
All to the other times I have flown I have not had any problems with being diabetic. I flew out of TJ for my honeymoon a year and a half ago to Ceurnavaca, Mexico and had not problems.
I do not use a pump but I don't think it should cause you problems.
I agree with the doctor's letter... it is a good thing to have with you, just in case.
Blessings from Ensenada, Mexico
I flew out of TJ several years ago with no problems at all. I am on pump and always take syringes with me also.