Francine R. Kaufman

Insulin Pumps and Continuous Glucose Monitoring


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REMEMBERING BACK TO DAY ONE

      I bet you can remember the day you found out you or your child had diabetes. It is likely that you knew something was wrong for a few days—maybe even weeks—before the diagnosis was made, but you thought it was the flu or a new phase in your life or in your child’s development. It is possible you even called your doctor and were told that the problem would go away soon and that there was likely nothing to worry about. Obviously, that wasn’t the case.

      Some children, teens, and adults are diagnosed with diabetes very early in the process, before they become sick. Some are diagnosed only after they become seriously ill. But most have some, if not all, of the typical signs and symptoms of diabetes: frequent urination, increased thirst, weight loss, and fatigue. These signs and symptoms occur because the pancreas can no longer make enough insulin. Without enough insulin, multiple problems occur with metabolism within the body.

      And now remember how remarkable it was just a few days after you were given insulin by injection or through an intravenous infusion (an IV). You were back to your usual self—active, hungry, gaining weight, and learning all about diabetes.

      Look back at the first tasks you were asked to do: you had to start to give insulin shots and check blood glucose levels before you had even had a chance to adjust to the fact that you had diabetes. In those first days, you were mostly asked to read, study, and listen to lectures about this disease. You must have felt overwhelmed as it became apparent you were expected to become an expert, something that took me (and all my health-care-provider friends) years and years to accomplish.

      You were likely given a list of things to do and a schedule of when to do them after you were first diagnosed, like in the example above. But essentially, by this time you were aware that every day you need to:

      1. Take insulin to be able to metabolize food (mainly carbohydrate) and control the release of glucose from body stores

      2. Measure glucose levels throughout the day and night to determine whether insulin doses are working properly

      3. Eat a healthy and balanced diet, understand the quantity and quality of food, and couple food with taking insulin

      4. Be physically active and understand the role of activity in glucose management.

      So see how far you have come from those first days? You have come far enough to now consider using an insulin pump and a continuous glucose monitor (CGM)—and to stay committed to doing what you can to optimize your journey with diabetes.

      In a person who does not have diabetes, the body is designed to control glucose levels in the blood in a very tight range. Although there are fluctuations of glucose levels throughout the day and night, generally glucose levels fall between 70 and 140 mg/dL— highest after eating and lowest after fasting (not eating). Insulin is secreted to keep the glucose that is released from your food or your body’s stores moving into your body’s cells, where it is used as fuel.

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      Insulin is secreted in two ways: 1. background (called basal insulin), and 2. surges (called bolus insulin).

      1. Background (or basal) insulin controls the glucose levels between meals and overnight. It is mainly acting to help regulate how much glucose is released from the stores in the liver (where it is stored as glycogen). The release of glucose from the liver between meals is critical for providing energy so the body’s cells can function. Without enough background or basal insulin, your liver would release too much glucose into the bloodstream and your cells would not be able to use it for energy. This could result in very high blood glucose levels. Additionally, without background insulin, the liver will start to produce acidic ketone bodies from the breakdown of fat. Like sugar, these ketone bodies can be measured in the blood and in the urine. As ketones build up in the bloodstream, there is the risk of developing diabetic ketoacidosis (known as DKA). This is potentially a very dangerous condition.

      2. Surge insulin (or bolus) occurs at mealtime. As glucose levels rise from meals, the pancreas responds with a large increase in insulin release, so the glucose can be used by the body’s cells. In the human body without diabetes, these surges are very precise: eat more, and more insulin is released; eat less, and less is released.

      With diabetes (always in type 1 and sometimes in type 2), the ability to release insulin is lost. Since the discovery of insulin, replacement insulin therapy has evolved into the modern system we have today. The older system used a fixed approach to insulin replacement (though this is still used today). Although you took only one to three shots a day, you had to take injections at set times and in set amounts. You had to eat the same amount of food at the same time every day, and you had to exercise at the same time every day. With this old way, keeping glucose in the target range was very difficult. And there was no flexibility in life. Essentially, your life had to fit into the diabetes regimen. The diabetes regimen controlled you.

      The newer way to treat diabetes is with flexible regimens: multiple daily injections (MDI) or insulin pump therapy. These newer, flexible systems mimic the way the pancreas normally produces and releases insulin. MDI mimics background insulin and surges of insulin. It allows you to deliver insulin in doses to match your food intake and gives you flexibility in how much you eat and when you eat it. You can be active when you want, and with an insulin pump you can decrease basal insulin in order to avoid hypoglycemia. You can sleep when you want, wake up late, and travel around the globe with the flexibility to change from one day to the next.

      You are likely taking multiple injections of insulin every day—possibly two or three injections (perhaps using NPH insulin)—but you are most likely on MDI. With MDI, you use rapid-acting insulin and long-acting or basal insulin. These two different kinds of insulins have different jobs, but both work to keep your glucose in the target range.

      Basal insulin is given as one or two shots each day, and it activates slowly after injection. This means that some amount of insulin will always be present in the blood. The blood can then bring insulin to the cells throughout the body, and glucose can then enter the cells, where it is converted into energy. In the liver, insulin helps regulate the slow release of stored glucose to meet the energy needs of the body’s cells between meals and during the night.

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      Bolus insulin is given as rapid-acting insulin. It is activated much faster after injection and brings the large amount of glucose from your meals into your body’s cells. There, glucose can be used right away for energy or stored for later use. Boluses with rapid-acting insulin can also be used to decrease a high blood glucose level. These doses are called correction boluses.

      The difference between an insulin pump and MDI is that an insulin pump just uses rapid-acting insulin to do both jobs. The basal rates on the pump replace the basal insulin injection in MDI, and boluses given at meals and for correction replace the mealtime and correction shots.

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      What is the ultimate goal of diabetes treatment?