How do I get c peptide test when my practice say the lab wouldn’t process it as levels not hI’ve enough?? Was on slow release metformin 500mg twice a day but after a few weeks of persevering with stomach issues (sometimes been violently sick) came off them. Sugar level erratic but metformin hadn’t been very helpful with that. Have been advised re c peptide test as that will tell me what insulin I am producing rather than playing Russian roulette with medication.