It depends on the cost of the prescription in Mexico and Belize. I have been living in China for 11 years, and althought I have my insulin covered, I often just buy extra out of pocket so that I have 6 - month worth of insulin because it is affordable to simply buy it from the pharmacy. You may want to consider that. Or, if possible, stock up now, if your insurance allows you to get more than x months of medicine at once.