A 78-year-old woman presented with a 3-day history of abdominal pain, nausea, vomiting, and anorexia. Past medical history included type 2 diabetes mellitus, autoimmune hepatitis, hypertension, and ulcerative colitis with colectomy. Medications included metformin 1500 mg twice daily (6 months), glyburide, rofecoxib, furosemide, levothyroxine, prednisone, azathioprine, and propanolol. On admission, she was hypothermic (34.41C), had blood pressure, 115/51 mm Hg, pulse 104 beats/min, and trace of lower extremity edema. The rest of the physical examination was unremarkable. Arterial blood gases showed pH 7.0, pCO 2 7 mm Hg, tCO 2 2 mEq/l. She was transferred to the intensive care unit and intubated for respiratory failure. Serum creatinine was 8.9 mg/dl (baseline, 1.0 mg/dl; estimated glomerular filtration rate (eGFR) 57 ml/min/1.73 2 by the Modification of Diet in Renal Disease Study (MDRDS) formula); serum lactate 9.6 mg/dl; serum metformin 17 mg/ml (therapeutic level 1-2 mg/ml). Liver enzymes were normal. Urinalysis: protein 2 þ and moderate blood. Renal ultrasound ruled out obstruction. Echocardiogram showed normal left ventricular function and all fluid cultures were negative. Pertinent laboratory findings are shown in Table 1.Patient 2: A 64-year-old woman presented with nausea and vomiting. Past medical history included type 2 diabetes mellitus, hyperlipidemia, and hypertension. Medications included metformin 500 mg twice daily (3 months), lisinopril, and ibuprofen for arthritis. On admission, she was hypothermic (34.