Diabetes and Lipid Clinic of Alaska



About insulin pumps

An insulin pump is a computerized device that delivers insulin to patients automatically 24 hours a day. Growing numbers of people with diabetes use insulin pumps, especially patients with type 1 diabetes. They also benefit some people with type 2 diabetes who need insulin.

Pumps have been used with schoolchildren, teen-agers and adults. They have also been used with diabetic infants and toddlers, with pumps that parents can operate by remote control.

Insulin pumps offer lifestyle flexibility because they pump insulin slowly and continuously in an imitation of the human pancreas. However, unlike the pancreas they do not make automatic adjustments based on the body’s needs. As with other forms of insulin administration, patients must be vigilant in monitoring their glucose (blood sugar) levels and, when necessary, adjusting their insulin dosage according to their physician-approved treatment plan.

Insulin pumps are about the same size as a cell phone or a pager and generally weigh about 3 ounces (85 grams), though some models weigh little more than 1 ounce. The pump and its delivery system are composed of the following parts:

  • Pump reservoir or insulin cartridge similar to that used in insulin pens.
  • Battery-operated pump. The type of battery used varies according to the model. Some batteries last only a few weeks, others two or three months.
  • Computer chip that controls how much insulin is delivered to the patient. The number of insulin rates and insulin profiles offered depends on the model. The basal range and the smallest bolus amount also vary according to model.
  • Thin plastic tube. The tube from the pump has a needle-like plastic or metal tip (cannula) that is inserted under the skin, or the tube is connected to another small, soft tube (catheter) that has been inserted into the skin. A cannula is changed every few days. The junction between the tube and the cannula is called an infusion set, but often that term is used to describe the cannula or catheter. At least one model of insulin pump has an integrated cannula and does not require tubing.

The various models also offer extra features. These may include a glucose meter, food database, bolus calculator or data storage. Some infusion sets include automatic insertion devices, and some do not need insertion devices.

The insertion site is the same used when insulin is injected, usually the fatty tissue of the abdomen but possibly the thigh or arm. Insertion of the needle causes no more discomfort than injection by syringe. Use of pumps may require needle insertion only every few days rather than several times a day.

The infusion set is taped into place on the patient’s body. When this is done properly, the patient does not feel it throughout the day or night. The tube and pump can be temporarily removed from the infusion set for activities such as contact sports.

Insulin pumps can be kept in a pocket or attached to a belt, shirt, underwear or other garments. The pump reservoir or cartridge holds two- to-three days’ worth of short-acting insulin. The small battery-powered pump pushes a plunger to force the gradual delivery of medication out of the pump, through plastic tubing and into the cannula. Insulin empties out of the cannula and is absorbed into the body. This method of delivering insulin is known as continuous subcutaneous insulin infusion.
Insulin pumps deliver the medication in three ways:

  • Basal rate. This is a continuous trickle of insulin that keeps blood glucose levels stable overnight and between meals. Many pumps allow patients to set different basal rates throughout the day. Thus, a patient can program basal rates appropriate to levels of activity such as sleep or exercise. 
  • Bolus rate. This is a surge of insulin that occurs shortly before a person eats and prepares the body to break down the glucose in the food about to be ingested. Patients who use insulin pumps push a button to provide bursts of insulin just before a meal or snack.
  • Corrective or supplemental doses

Insulin pumps are worn 24 hours a day, including overnight while the patient sleeps. This does not cause discomfort. Occasionally, patients may remove the pumps for an hour or two to engage in certain activities. These include athletics, showering and intimacy. At least one brand of insulin pump is described by the manufacturer as waterproof. However, most are merely water-resistant, and they should be removed for bathing and swimming, according to the American Diabetes Association (ADA).

Infusion sets need to be replaced every one to three days. For information on disposal of medical waste, see Syringes. Individuals are advised to rotate the insertion site according to their physician’s recommendation.

Patients who use insulin pumps must make a serious commitment to the treatment. Training may take a day or longer. Patients are required to perform glucose monitoring on the schedule recommended by their physician (generally every three or four hours, according to the ADA), and to keep a close watch on carbohydrate consumption. When pumps quit delivering insulin for whatever reason, dangerously elevated glucose levels can quickly result. This requires immediate attention.

Pumps come with built-in warning systems that alert patients when insulin flow has been halted, batteries are low or other conditions have arisen that require the patient’s attention. Patients who use insulin pumps may discover high glucose levels (hyperglycemia) during periodic testing. This can be the result of many factors, including:

  • Clogged or kinked tubing that prevents insulin from reaching the patient
  • Infection or inflammation at the insertion site
  • Expired or damaged insulin
  • Empty insulin cartridge
  • Problems with the infusion set, such as dislodged needle or cannula
  • Worn-out batteries

Pumps can be temporarily removed during certain activities. However, patients generally should not keep their pump detached for more than one or two hours. Some activities that tend to lower glucose levels may allow the patient to stay detached from the pump for longer periods of time. However, individuals should discuss this beforehand with their physician.

Potential advantages of insulin pumps

There are several advantages to using insulin pumps to deliver medication. These include:

  • Increased lifestyle flexibility. Because pumps meet both basal and bolus insulin needs, they eliminate the need for long-acting insulin.  Patients also can eat meals when they desire instead of scheduling them according to when their insulin levels are peaking.
  • Predictable and precise insulin delivery. Insulin pumps allow patients to deliver precise amounts of insulin down to 1/10 of a unit.
  • Tighter glucose (blood sugar) control and reduced risk of low glucose (hypoglycemia). Insulin delivered via a pump is not put into the body until it is needed, which can mean fewer insulin-based reactions

Potential disadvantages of insulin pumps

Although insulin pumps offer some advantages over other methods of Insulin can be administered by syringe, pump and other ways.insulin administration, they also come with potential drawbacks.

These include:

  • Risk of infection. Bacteria and other harmful organisms may enter the insertion site. Diabetes makes infections harder to control.
  • Risk of ketoacidosis. Dangerously high levels of a waste product called ketones can form in the blood because of pump malfunction or problems with insulin absorption. For more information, see Diabetic Ketoacidosis.
  • Higher cost than injection therapy. Pumps can cost thousands of dollars, and supplies can cost hundreds of dollars a month. Health insurance may cover some of this expense.
  • Patient commitment.  Although convenience is one of the major advantages of using insulin pumps, the devices still require a major commitment on the part of the patient. Patients using insulin pumps need to check glucose (blood sugar) as recommended by their physician, generally at least four times each day. They must be prepared to react quickly if something goes wrong with the pump. If pumps quit delivering insulin for whatever reason, dangerously elevated glucose levels (hyperglycemia) can quickly result. Pumps have built-in alarms that sound a warning when the pumps need attention.
  • Loss of privacy. The pump may reveal the patient’s diabetic condition to others. This can be an issue, especially for children and teens sensitive to how they are perceived. However, in many cases pumps can be attached to underclothing

Ongoing research on insulin pumps

Insulin pumps have been used primarily by people with type 1 diabetes but are also being used by people with type 2 diabetes who are insulin-dependent. Recent research indicates that pumps and syringe injections are comparably effective in treating type 2 diabetes.

In general, insulin pumps decrease the risk of severe hypoglycemia (low glucose), according to the American Diabetes Association. However, one recent study of children and adolescents with type 1 diabetes suggested that use of an insulin pump during exercise may raise the risk of hypoglycemia long afterward. Individuals are advised to ask their physician about whether to keep their pump on during exercise.

Implantable insulin pumps promise to be the next wave in pump therapy. These pumps are still under development, but are intended to be surgically implanted on the left side of the abdomen. The disk–shaped device weighs about 6 ounces to 8 ounces (about 200 grams) and delivers a continuous basal dose of insulin. Bolus doses can be controlled via a remote control unit. The pump would be refilled with insulin every two or three months.

Eventually, it is also hoped that insulin pumps will be able to sense when the patient needs insulin and to deliver an appropriate dose of insulin. This would eliminate the patient’s need to consistently check glucose (blood sugar) levels.

For further information, please contact the medical professionals at the Diabetes and Lipid Clinic of Alaska.

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