A nurse is caring for a patient with newly diagnosed type II diabetes mellitus who has been ordered to begin metformin. The nurse knows that the presence of which of the following in the patient’s medical history would represent a contraindication to this therapy?

Metformin is an oral biguanide antidiabetic agent that reduces the hepatic production of glucose and increases peripheral insulin sensitivity. It is primarily eliminated by the kidney, and its use in a patient with moderate to severe renal impairment is contraindicated. Other contraindications include diabetic ketoacidosis, metabolic acidosis, and lactic acidosis. It is also not advisable to use during pregnancy. Uncontrolled hypertension and seizure disorder are not contraindications for metformin, and it may be helpful in the treatment of polycystic ovary syndrome (PCOS).