I am a trainer of service dogs and yes, service dogs can be trained to detect low blood sugar levels. They are also trained to detect impending seizures, used is Parkinson's disease for stabilization and tremors, and have even been trained to sniff out cancer. They are wonderful creatures and we have only scratched the surface of what things they can help us with.
Sharon Hall, MT(ASCP)SH
Hearts of Gold Service Dogs Volunteer