[CME: Metformin - Dos and Don'ts].

CME: Metformin - Dos and Don'ts Abstract. In the absence of contraindications metformin is still considered the initial medication in patients with diabetes mellitus type 2, although diabetes therapy is rapidly changing. Metformin is used both as monotherapy and in combination with any other diabetic medication. As a biguanide metformin improves glycemic control by inhibiting gluconeogenesis and increasing insulin-mediated glucose utilization in peripheral tissues. Metformin promotes modest weight reduction and provides several other advantages: no risk of hypoglycemia, excellent general tolerability, well-known long-term safety profile and low-cost. The most common gastrointestinal side effects are usually mild and transient, but vitamin B12 deficiency may develop. Metformin-associated lactic acidosis (MALA) is a rare, but relevant and life-threatening complication. The risk increases with renal impairment; therefore the metformin dose must be adjusted to the eGFR. The use of metformin is contraindicated with an eGFR <30 ml/min/1.73 m2. There are other contraindications: concurrent active or progressive severe liver disease, active alcohol abuse, unstable or acute heart failure, hypoperfusion and hemodynamic instability, as well as a past history of lactic acidosis. Since metformin remains a modern therapy, it is important to be aware of its indications and contraindications.