Thrush is a symptom and I had it as well, I insisted my doc for it though i was quite confident i would not have it as no one in the family has it and I eat very healthy but i would say moderate on exercise, daily commute for me to and from work in London is enough to make me walk for about a mile everyday, i would really insist them to have the blood test done, alternatively if they keep saying they cant or wouldn't, just buy a cheap meter as other members suggested.