What Causes Dizziness Followed By Diarrhea While Having Diabetes?

I get dizzy after I have diaherria Been happening over a year off and on I asked Gastro doctor and she said to tell my family doctor Since it was only sometimes I never bothered Today I was in a store and nearly passed out after D Paramedics came and said heart rate was 38 After 15 min it was back up to 80 Feel fine now. Usually if this happened at home I just sat for awhile and I felt better Paramedics done EKG and heart looked ok. I do have diabetes and sugar was 107.