Pharmaceutical compositions of the active substances glimepiride with metformin or its salts such as hydrochloride, succinate, furmarate, etc. are useful to control blood glucose in patients with type 2 diabetes. To prove the effectiveness of the combination, clinical studies were conducted that demonstrated the existence of not only an additive effect, but also a synergistic effect of the two drugs compared with monotherapy using only one of the drugs used in combination. In consequence, the combination may be used as an effective and safe therapy to control blood glucose in patients with type 2 diabetes, using different proportions of the active substances in combinations suitable for the needs of different patients.