I take metformin...some days no side effects, other days i have diarrhea...how come? do too many carbs

Metformin: Metformin is a drug that helps make you more sensitive or responsive to insulin. It's shorter acting form has a greater risk of causing upset stomach ; diarrhea compared to it's longer acting version. Assuming you're not mixing ; matching different pills, it's not clear why you'd have diarrhea some days ; not others. More likely, it's due to what you eat rather than metformin. Go see ur family doc.

It's complicated: Track the episodes of diarrhea and look at what you have eaten, circumstances, blood sugar levels. Try to find pattern which will inform you about possible cause. From there you may be ale to control the diarrhea by changing dose, timing, or frequency of medication. High blood sugar may worsen symptoms. A high protein, plant based, extremely low carbs diet are good habits.

Poor tolerance: Side effects from metformin can be dose related and even cumulative. Try a lower dose and then slowly increase as your body gets used to it. You can even ask your doctor for long acting formulation which is sometimes better tolerated.