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 some, including anyone with type 1 diabetes, need artificial sources of insulin that can be delivered by injection or 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 adjust their insulin dosage as necessary.

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.