Sitagliptin and metformin is contraindicated in patients with: hypersensitivity to the active substances or to any of the excipients; any type of acute metabolic acidosis (such as lactic acidosis, diabetic ketoacidosis); diabetic pre-coma; severe renal failure (GFR < 30 mL/min); acute conditions with the potential to alter renal function such as: dehydration, severe infection, shock, intravascular administration of iodinated contrast agents; acute or chronic disease which may cause tissue hypoxia such as: cardiac or respiratory failure, recent myocardial infarction, shock; hepatic impairment; acute alcohol intoxication, alcoholism; breast-feeding.