I recently returned from a trip to Wyoming that I took with my family.  On the plane ride back, we had a layover, and when we got off the first flight, my dad couldn't find his blood tester.  A blood tester is crucial for a diabetic because it gives them an exact reading of their blood sugar level and allows them to take the appropriate amount of insulin if necessary.  Naturally, we were all worried and nervous when the blood tester was no where to be found.  My dad assured us that he would be fine, but everyone still took extra precautions.  We woke him up every 30 minutes on the flight back to New York, and always asked him how he was feeling.  The next day, after returning home, the first thing my dad did was buy an extra blood tester that either my mom, my brother, or I can carry if when we travel.  Even though it was a scary experience, now we will always be prepared if something happens in the future.  Find out if someone you know with diabetes travels with an extra blood tester! 
If you want to take an extra precaution and carry a blood tester, I recommend the OneTouch UltraMini which is extremely small and portable - my dad uses it.