I have heard that we can give subcutaneous (SC) regular insulin every one to two hours instead of giving an IV infusion. Is that true?—Dennis A. Fito, MD, Oklahoma City

While in theory this may be true, practically speaking, the varied absorption rates of SC insulin make this an unreliable way of managing conditions that require IV insulin therapy. The short half-life of insulin (approximately eight minutes) makes IV insulin therapy in a monitored setting (ICU or emergency department capable of managing diabetic ketoacidosis or hyperglycemic hyperosmolar nonketotic coma) a superior way of titrating insulin and more importantly glucose levels. If one were to rely on repeated SC shots of regular or rapid-acting analog insulins, the duration of action of these and the potential for “stacking” of insulin effect from consecutive administration would make it hard to titrate the doses accurately.—Lyle Mitzner, MD (131-4)