I've had a lot of reflexology treatments in the past from my aunt who is a trained reflexologist. She warned me before I had treatment that it may affect my blood sugar - ie I had to watch out for a hypo afterwards. I think it only happened to me once but it's something to be careful of. I also think it may have been because I was much younger and more newly diabetic, therefore possibly had some remaining insulin being produced that was stimulated by the treatment.
So just be careful... have something ready to eat in case you need it.