The Joint Commission has published an official “Do Not Use” list of abbreviations that are a frequent cause of medication errors and are no longer to be used when writing medication orders. These abbreviations include “u” for “unit” and “qd” or “qday” for daily. The abbreviation for subcutaneous (subQ) is appropriate. Therefore, the most appropriate order is, “5 units regular insulin daily subQ before breakfast,” as it precisely gives the dose, drug, route, time of administration, and frequency of the medication while using appropriate abbreviations. Orders with “u” and “qd/qday” are inappropriate as using these abbreviations leads to increased medication errors.