Metformin prevents the production of sugar from fats in the liver. (Gluconeogenesis GNG) My partner noticed was that, if he fasts while on Metformin, blood suga

Metformin prevents the production of sugar from fats in the liver. (Gluconeogenesis GNG) My partner noticed was that, if he fasts while on Metformin, blood sugar levels got seriously low. Around 40 mg/dL. I guess GNG keeps blood sugar levels high enough to prevent issues while ketones take over the energy economy. So if you are fasting for more than a couple days you may want to skip that metformin dose.