Insulin Regimens

Insulin Regimens

A. Intensive Insulin Therapy

Intensive insulin regimens are prescribed for almost everyone with type 1 diabetes—diabetes associated with a severe deficiency or absence of endogenous insulin production—as well as many with type 2 diabetes.

Generally, the total daily insulin requirement in units is equal to the weight in pounds divided by four, or 0.55 times the person’s weight in kilograms. Approximately half the total daily insulin dose covers the background or basal insulin requirements, and the remainder covers meal and snack requirement and high blood sugar corrections. This is an approximate calculation and has to be individualized. Examples of reduced insulin requirement include newly diagnosed persons and those with ongoing endogenous insulin production, longstanding diabetes with insulin sensitivity, significant renal insufficiency, or other endocrine deficiencies. Increased insulin requirements typically occur with obesity, during adolescence, during the latter trimesters of pregnancy, and in individuals with type 2 diabetes.

In intensive insulin regimens, the meal or snack and high blood sugar correction boluses are prescribed by formulas. The patient uses the formulas to calculate the rapid-acting insulin bolus dose by considering how much carbohydrate is in the meal or snack, the current plasma glucose, and the target glucose. The formula for the meal or snack bolus is expressed as an insulin-to-carbohydrate ratio, which refers to how many grams of carbohydrate will be disposed of by 1 unit of rapid-acting insulin. The high blood sugar correction formula is expressed as the predicted fall in plasma glu-cose (in mg/dL) after 1 unit of rapid-acting insulin. Diurnal varia-tions in insulin sensitivity can be accommodated by prescribing different basal rates and bolus insulin doses throughout the day. Continuous subcutaneous insulin infusion devices provide the most sophisticated and physiologic insulin replacement.

B. Conventional Insulin Therapy

Conventional insulin therapy is usually prescribed only for certain people with type 2 diabetes who are felt not to benefit from inten-sive glucose control. The insulin regimen ranges from one injec-tion per day to many injections per day, using intermediate- or long-acting insulin alone or with short- or rapid-acting insulin or premixed insulins. Referred to as sliding-scale regimens, conven-tional insulin regimens customarily fix the dose of the intermediate-or long-acting insulin, but vary the short- or rapid-acting insulin based on the plasma glucose level before the injection.