M58, is it necessary that metformin decrease blood sugar levels in each and every person that uses it.

Mainly for diabetes: Metformin works by suppressing glucose (sugar) production by the liver, decreases glucose absorption in the gut and increases insulin sensitivity. Also metformin has been used to treat polycyctic ovarian syndrome in women, as they have insulin resistance and in obese patients to loose weight. Metformin also improves the lipid (cholesterol) profile in diabetics.