I'm a type one insulin dependent diabetic and walked in 2016. I carried insulin in a Frio pack, which kept it plenty cool for April/May temps. With the frio packs, they are a gel that needs to be kept soaked in water. Mine never dried out. I over-soaked it, actually, and the crystals expand to where it's hard to fit the insulin in it. I carried twice as much as I needed, but it doesn't weigh that much. I allowed for dropping a bottle and breaking it, but didn't have any of those kind of problems. I also carried paper and e-copies of my prescriptions from my Dr.'s, and as diabetes is not limited to Americans, know if I needed I could visit a hospital, clinic or pharmacia in Spain and get them filled if really necessary. Customs was not an issue. I also used a lot less insulin than normal as we're burning off so many calories, and as a result, had even more than I thought I might need. I wouldn't use the albergue refrigerators as I didn't want to chance forgetting them or someone else taking them by mistake. Packing insulin is nothing to worry about. I worried more about having open blisters on my feet and infecting them in albergue showers, a big no-no for diabetics. I found leaving early and quitting early provided me a bed and clean showers.