Updated April 26, 2005

Insulin Therapy for Type 2 Diabetes

by Virginia Peragallo-Dittko, R.N., B.C.-A.D.M., M.A., C.D.E.

Insulin inconvenience. It’s true; it is easier to take pills. However, newer insulin delivery devices minimize the inconvenience of taking injections, and insulin regimens can be tailored to your needs and your routines to make it easier.

Permanent or temporary?
In the treatment of Type 2 diabetes, insulin therapy may be prescribed for a variety of reasons and may be permanent or temporary. For example, some people require short-term, or temporary, insulin therapy when they take certain drugs such as steroids to treat other medical conditions. Because steroids such as prednisone can cause extremely elevated blood glucose levels, insulin may be used to lower blood glucose levels during steroid use. Generally, when the steroids are discontinued, the person no longer requires insulin therapy.

Infection or long periods of untreated diabetes may cause a condition called glucotoxicity. When someone is glucotoxic, elevated blood glucose levels interfere with the body’s ability to lower blood glucose. Short-term insulin therapy is used to lower blood glucose levels, eliminating the glucotoxicity and restoring the body’s normal glucose regulation.

Effective treatments for insulin resistance include weight loss, exercise, and insulin-sensitizing medicines such as pioglitazone (Actos), rosiglitazone (Avandia), and metformin (Glucophage). But some people may also require large doses of injected insulin, at least initially, to get past the barrier of insulin resistance and keep their blood glucose within range. Once these people have lost weight and begun exercising, they may be able to discontinue insulin therapy—as long as their pancreas continues to produce insulin. But people who have both insulin resistance and a pancreas that cannot secrete enough insulin require permanent insulin replacement.

Insulin replacement strategies
Just as there are different reasons to use insulin therapy, there are different formulations of insulin that are prescribed based on what your body needs. To get past the barrier of insulin resistance or to combat glucotoxicity, long-acting or intermediate-acting formulations of insulin may be prescribed. Long-acting insulins, which include Ultralente and the insulin analog glargine (Lantus), are typically injected at bedtime and are usually effective for up to 24 hours. Intermediate-acting insulins, which include NPH and Lente, are also often injected at bedtime but are effective for only 12 to 16 hours.

When both insulin resistance and inadequate secretion of insulin by the pancreas are the problem, two different insulin formulations are needed: one long-acting, or basal, insulin and one short-acting, or bolus, insulin. The long-acting insulin supplies the low-level, background insulin needed by the body at all times; the short-acting insulin supplies the insulin your body needs at mealtimes to handle the glucose from food. So-called “mealtime” insulins include Regular and the rapid-acting insulin analogs lispro (Humalog) and aspart (NovoLog).

Some people who need both long-acting and short-acting insulins use premixed insulins such as Humulin 50/50, Humulin 70/30, Novolin 70/30, Humalog Mix 75/25, or NovoLog Mix 70/30. A dose of 50 units of Humulin or Novolin 70/30 provides a combined basal, intermediate-acting insulin (NPH) dose of 35 units and a bolus, short-acting insulin (Regular) dose of 15 units. Other people mix their own long-acting and short-acting insulins or take each separately.

Practical concerns
If you are considering insulin therapy or if your health-care team is recommending insulin therapy, you’re probably wondering about the day-to-day mechanics of using insulin. Although this is not an exhaustive list, it may help you to get an overview of the subject.

Timing of injections. Taking your injections around the same time of day is important because insulin formulations release insulin into your system over a period of time, and although some basal insulins maintain a rather constant level of insulin in your bloodstream, other increase, peak, and decrease. If you inject your NPH insulin at 6 PM one night and 11 PM another night, you will see potentially wide variations in your blood glucose levels.

Virginia Peragallo-Dittko is a diabetes nurse specialist and Director of the Diabetes Education Center at Winthrop-University Hospital in Mineola, New York.

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