Can having c-diff for 8+ months cause blood sugar levels to increase? How should it be treated? Do i wait for the c-diff to be resolved. I ve been on flagyl once, vanco pills(1) and the oral suspension vanco, and dificid. In 8 months i was negative for only 4 days when onset symptoms began again. I ve had one FMT waited 7 weeks, syptomatic the entire time, stool culture came back positive. My glucose has gone up to levels I ve never had, my a1c has never been above 6, got c-diff, it s been 11.3 and 12 today.