The present invention is directed to a liquid formulation of metformin or its pharmaceutically acceptable salts thereof. The liquid pharmaceutical composition comprises a therapeutically effective amount of metformin or its pharmaceutically acceptable salt, in a liquid carrier, which may also include a sweetener that does not increase the blood glucose level of a subject after ingestion thereof. In one embodiment, it may also include alkyl hydroxyethylcellulose, and/or a polyhydroxy alcohol. In another embodiment, the carrier may contain a sweetener, mineral acid, and bicarbonate salt maintained at a pH of 4.0 to 9.0. It is useful for treating hyperglycemia and diabetes.