Take Metformin with food. Ask your doctor about the best time to take Metformin. Most of the time Metformin is taken with the evening meal. Have your blood tested regularly while taking Metformin.Be sure to make it to every appointment to have your blood and kidney functions analyzed.Swallow Metformin whole.ost of the time Metformin is taken with the evening meal. Have your blood tested regularly while taking Metformin. Be sure to make it to every appointment to have your blood and kidney functions analyzed. Swallow Metformin whole.