Metformin × Zinc (oral salts: picolinate, citrate, gluconate, oxide, acetate)

Zinc theoretically competes with metformin for renal tubular organic cation secretion, but no clinically significant hyperglycaemia has been described on the combination.

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

No dose adjustment needed. In diabetics with zinc deficiency (e.g. on a vegan diet), zinc supplements 15–25 mg/day are safe. Monitor HbA1c on the usual schedule.