An insulin pump is a small device that delivers insulin to patients with diabetes. Insulin is a hormone needed to control glucose (blood sugar), the body’s main fuel. People with diabetes have problems using and producing insulin and may need artificial sources of insulin such as a pump.

Insulin pumps release 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 with glucose monitoring and, when necessary, adjust their insulin dosage.

Insulin pumps are about the size of a cell phone and are usually worn on a belt or in a pocket. They operate throughout the day and night to deliver the medication in three ways:

• Basal rate. This is a continuous trickle of insulin that keeps glucose levels stable overnight and between meals. Many pumps allow patients to set different basal rates to account for activities such as sleep or exercise. 
  
  
• Bolus dose. This is a surge of insulin that occurs shortly before a person eats.
  
  
• Corrective or supplemental doses.

Insulin pumps allow patients to control glucose levels with a minimal disruption to their lives. For example, patients using insulin pumps do not have to plan their mealtimes and activities to correspond to certain periods of peak insulin activity.

However, people who use insulin pumps must take an active role in managing their care. Patients often have to adjust dosages based on glucose levels, carbohydrate intake, exercise and other factors. They must also commit to checking glucose several times a day as advised by their physician and keeping a close watch on consumption of carbohydrates.

In addition to the external devices, there are surgically implantable insulin pumps.

An insulin pump is a computerized device that delivers insulin to patients throughout the day and night. Growing numbers of people with diabetes use insulin pumps, especially patients with type 1 diabetes. They also benefit some people with type 2 diabetes or other forms of diabetes who need insulin.

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

Insulin pumps offer 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 size of a cell phone 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.
  
  
• 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. Recent innovations include a unit combining an insulin pump with a continuous glucose monitor. One alternative system has a replaceable self-adhesive insulin-filled pod that is attached to the skin for several days and controlled by a wireless handheld gadget.

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 dose. 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 rapid-acting insulin can make their pump provide a burst of insulin around mealtime. Those who use regular insulin may be instructed to take a bolus dose about half an hour before eating.
  
  
• 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 activities such as athletics, showering or intimacy. Some pumps are described by the manufacturer as waterproof and submersible but not recommended for use in a sauna or steam room. 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. 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 consumption of carbohydrates. When pumps quit delivering insulin for whatever reason, dangerously elevated glucose levels can quickly result. This hyperglycemia 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 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.

Surgically implantable insulin pumps are being developed as an alternative to external devices.

There are also other ways of delivering insulin besides pumps and traditional syringe injections. These include:

• Insulin pen. A device resembling a fountain pen that is used to inject cartridges of insulin.
  
  

• Insulin jet injector. A pen-like device that uses high pressure to propel insulin through the skin and into the body.
  
  
• Inhaled insulin. Powdered insulin that is delivered through the mouth with a special inhaler. In addition, nasally delivered insulin sprays are being developed.

In addition, some people who use insulin may be candidates for a pancreas transplant or an islet cell transplant.

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 administer precise amounts of insulin down to 1/10 of a unit.
  
  
• Tighter control of glucose (blood sugar) and reduced risk of low glucose (hypoglycemia) and insulin shock. Insulin delivered via a pump is not put into the body until it is needed, which can mean fewer insulin reactions. They may particularly benefit people who have hypoglycemia unawareness (difficulty sensing low glucose).

Although insulin pumps offer some advantages over other methods of 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 diabetic ketoacidosis. Dangerously high levels of a waste product called ketones can form in the blood because of pump malfunction or problems with insulin absorption.
  
  
• 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.

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.

Pumps that are surgically placed in the abdomen promise to be the next wave. These implantable insulin pumps are still used only experimentally in the United States but are more widely available in some other countries. The disk-shaped device delivers a continuous basal dose of insulin. Patients administer bolus doses with a remote-control unit. The pump is refilled with injected insulin every two or three months.

The ultimate goal is development of an artificial pancreas that senses when the patient needs insulin and delivers an appropriate dose of insulin. This would eliminate the patient’s need to consistently check glucose (blood sugar) levels.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about insulin pumps:

1. Is an insulin pump an option for me?
   
   
2. What are their advantages and disadvantages compared to other methods of insulin administration?
   
   
3. Will my insurance cover an insulin pump and supplies, or is any financial assistance available to me?
   
   
4. Where will I go for training in using an insulin pump, and how long will training take?
   
   
5. What should I look for when buying an insulin pump?
   
   
6. Should I get a pump that includes a glucose meter, food database, bolus calculator, data storage, tube-free cannula or any other features?
   
   
7. Do you recommend any particular brand of insulin pump for me?
   
   
8. How many basal rates and profiles does this pump offer?
   
   
9. Which does this pump require: a catheter or a cannula?
   
   
10. How often should I replace the infusion set?
    
    
11. At what rate does my pump deliver insulin?
    
    
12. What type of insulin does my pump use, and how long will the cartridge or reservoir last?
    
    
13. What type of battery is used, and how often do I need to replace it?
    
    
14. How will use of an insulin pump affect my diet?
    
    
15. What insertion sites should I use, and how often should I rotate them?
    
    
16. How often should I change the catheter or cannula?
    
    
17. For how long may I remove my insulin pump for bathing, contact sports or romance?
    
    
18. Will use of my insulin pump during exercise increase my risk of hypoglycemia afterward?
    
    
19. When using an insulin pump, how often will I need to check my blood sugar?
    
    
20. What plan should I have in place in case my pump fails or another glucose emergency occurs?
    
    
21. Is an implantable insulin pump an option for me? If so, where are these available?