Which medications should be taken on the morning of surgery? A 31 yo M with type II DM takes Lantus, metformin, and glipizide.  

½ his normal dose of Lantus

According to the American Diabetes Association, patients should hold metformin the day before surgery as well as the day of the case. This is because metformin can contribute to lactic acidosis if the patient’s renal function is damaged intraoperatively. Patients should hold any other oral hypoglycemics only on the morning of surgery (Glipizide, pioglitazone, etc.) As this patient will be NPO for several hours before the case, taking his normal dose of Lantus will put him at risk for hypoglycemia. Current recommendations are for patients to take ½ to 1/3rd their normal amount of long-acting insulin and for the surgery to be early on the schedule if possible. Hourly blood glucose should be checked intraoperatively. See: https://clinical.diabetesjournals.org/content/19/2/92.full