By: Barry Ginsberg
In light of the results of the DCCT, Dr. Barry Ginsberg has written a three-part series on intensive insulin therapy. Look for the continuation of Dr. Ginsberg’s “How to Understand and Use Insulin” in future issues.
Part one of “Intensive Insulin Therapy” provides a definition of intensive therapy and an overview of the theories and techniques involved. The second part explains how to start an intensive therapy regimen, while the third deals with adjusting insulin doses when using intensive therapy. The goal of this series is to educate people with diabetes about intensive therapy and enable them to choose the therapy that is right for them.
Dr. Barry H. Ginsberg, MD, PhD, and Endocrinologist, is currently the Medical Director for Becton Dickinson. The opinions in this article are those of Dr. Ginsberg and do not necessarily represent those of Becton Dickinson and Company.
“Metabolic Control Matters”
This statement by Dr. Richard Eastman of the National Institutes of Health will change the way we care for diabetes in the U.S. and around the world. It was based upon the exciting and very powerful data of the Diabetes Control and Complications Trial (DCCT), a ten year study of more than 1400 patients with insulin-dependent diabetes mellitus. The study demonstrated a 50-70% reduction in the complications of diabetes with near-normalization of blood glucose. The study, one of the most positive of any large, multicenter clinical trial was so clear that Dr. Dan Foster, speaking for the American Diabetes Association and Dr. Phil Gordon, head of the National Institute of Diabetes, Digestive and Kidney Diseases of the National Institutes of Health stated that the results should be applied to patients with type 2 diabetes as well. Thus, the data now very strongly supports what most of us already believed: that normalizing blood glucose in diabetes will help prevent the complications of diabetes.
Why Intensive Therapy?
In the Diabetes Control and Complications Trial (DCCT) patients achieved near-normal blood glucose values by using intensive therapy for their diabetes. Intensive therapy is composed of intensive insulin therapy, intensive education, and intensive medical interaction with a diabetes health care team. Conversion to intensive therapy has been a slow process in the U.S., but other countries, particularly those of northern Europe, have been much quicker to adopt this ther-apy. In the U.S., intensive therapy accounts for only about 5% of all insulin therapy in type I diabetes, but in Sweden it is more than 70%. The very positive results of the DCCT will also serve to accelerate this movement.
Some Kudos for my Team:
Much of what I will describe to you was developed in the setting of the DCCT at the University of Iowa, where I was the Principal Investigator. Like many parts of our lives, this development was a team effort and I would like to thank the other members of the team, who all had input into this development process. Physicians: Robert Thompson, MD (now at Eli Lilly & Co.), William Sivitz, MD, Rod Zeitler, MD, Robert Hoffman, MD, and John MacIndoe, MD. Nurses: Margaret Bayless, BSN and Nancy Olson, BSN, MSN. Nutritionists: Linda Snetselaar, RD, PhD and Dru Kurtzman, RD, MS. Psychologist: Jon Kramer, PhD.
What is Intensive Therapy?
Intensive insulin therapy has been defined variously. The DCCT defined it as three or more injections of insulin per day but this just describes it and misses the essence of the therapy. Intensive insulin therapy is a different method of looking at diabetes therapy. In conventional insulin therapy you eat for your insulin (i.e. you alter your food to adjust for changes in your regimen after you have injected your insulin). In intensive insulin therapy you take your insulin to match your food.
In intensive insulin therapy you take an injection of insulin before each meal. This insulin is appropriate for the amount of glucose in the meal and the amount of exercise you will perform over the next few hours. It will maintain the same blood sugar over the next 4-6 hours after the injection. If you are going to vary the amount of food, amount of exercise, if your blood sugar is too high, or your blood sugar is too low, you alter the insulin that you take. This flexibility in the amount of insulin that you take provides better blood glucose control.
Using a regimen such as this provides significant advantages. It provides:
- Insulin in a more physiologic manner,
- Better blood glucose control,
- More flexibility in meal timing and amount,
- More flexibility for exercise,
- A sense of control over your life.
A person without diabetes produces a small amount of insulin all day and more when they eat (figure 1, thin line). When you utilize intensive insulin therapy, you obtain blood insulin levels that are more like those normally produced by the body (Figure, 1 thick line). This gives better blood glucose control with overall lower blood insulin levels.
Better Glucose Control
Intensive insulin therapy, given either with shots or an insulin pump was the method of choice for obtaining near-normal blood glucose values in the DCCT. A better real life test, however is provided by looking at the blood glucose values in a clinical diabetes center. One such set of values is provided in figure 2. The light gray bars are the patients on conventional insulin therapy. The median HbA1c was about 11. For comparison, the group on intensive insulin therapy had a median HbA1c of 7.5. For fairness, it should be noted that the patients presented in this data were neither randomized nor controlled, although the goal of the clinic was to achieve near-normal blood glucoses in all patients.
Intensive insulin therapy provides greater flexibility in both the timing of meals and the amount eaten. Regular insulin is given about a half hour before the start of a meal. If you will eat late, just remember to take your insulin about 30 minutes before your eat. The amount of insulin that you take is appropriate for a certain meal size. If you will eat more, take more insulin, if you will eat less, take less insulin. We’ll describe later, how to calculate this amount.
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Next month “Intensive Insulin Therapy” continues, and Dr. Ginsberg tells you how to start intensive therapy.