An insulin pump is a method of delivering insulin to patients who cannot make their own insulin--most often, patients with Type 1 diabetes. The insulin pump looks like a pager. It's connected to a long, thin tube called a catheter, which is placed under the patient's skin and delivers insulin. This delivery system may help patients with Type 1 diabetes prevent the high and low blood sugars associated with management of Type 1 diabetes. An important aspect of the pump is being able to program it in different types of basal patterns.
Daily Basal Pattern
The basal pattern of insulin delivery tries to replicate as closely as possible the background level of insulin that the pancreas of a non-diabetic person produces. This helps keep the pump user's level of blood sugar within his target range, between meals and when the patient is asleep. According to the University of California, San Francisco website, Diabetes Education Online, this is done by delivering a very small amount of insulin from the pump to the person every few minutes. The patient using the insulin pump can control this basal pattern by entering in how many units of insulin he wants the pump to deliver every hour. The pump uses this figure to determine how much insulin must be delivered every few minutes to maintain a consistent, steady amount of insulin over 24 hours. Pump users should realize that this rate of insulin is then delivered automatically, until the user changes the hourly rate. No extra programming is needed for the basal rate; the pump keeps on delivering this steady amount of insulin until the rate is changed or the insulin vial in the pump is empty and is replaced.
Temporary (Exercise/Illness) Basal Pattern
Temporary basal patterns are used when there are changes in a daily routine. An example of a relatively infrequent change to the usual routine is that of illness. When a patient with diabetes is sick, he needs more insulin than usual. A temporary basal pattern for a sick day can be programmed in by the pump user in the following way: First, he may enter in the new basal pattern, often as a percentage of his daily basal pattern. The user enters the amount of time for which the temporary basal pattern is to be used. Once these numbers are entered into the pump, the pump automatically changes from the usual basal pattern to the temporary pattern. Another useful time to use a temporary basal pattern is when a person exercises regularly. The American Diabetes Association notes that exercise increases the body's sensitivity to insulin; that is, the same amount of insulin may cause a bigger drop in blood sugar after exercising. Because of this, patients who exercise regularly, and who use an insulin pump, may want to consider programming in a temporary basal rate that's used on exercise days. This temporary basal pattern--for instance, 75 percent of the usual pattern--results in less insulin being delivered over 24 hours and may help decrease the chance for hypoglycemia that may occur in the hours following an exercise session.
Bolus Patterns
Besides the two main basal pump patterns, an insulin pump may be used to deliver a "bolus" amount of insulin. A bolus pattern of insulin is used just before meals containing carbohydrates. When a pump user wants to eat such a meal, she simply enters in the amount of insulin needed to cover the carbohydrates in the meal. This insulin does not replace the basal pattern; it's used in addition to the basal amount of insulin. A bolus dose of insulin, in combination with the "background," basal dose, prevents the pump user's blood sugar from reaching dangerously high levels after eating a carbohydrate-rich meal.
