How an insulin pump works
Like the pancreas of a person without diabetes, an insulin pump regularly releases small quantities of insulin into the body, 24 hours a day, as well as additional insulin when food is eaten. Multiple daily injection therapy aims to mirror this by providing long-acting insulin throughout the day, as well as bolus doses of fast-acting insulin at mealtimes.
Insulin pump therapy takes this further, by providing a steady level of insulin, called basal insulin, at rates that better correspond to the body's needs throughout the day. At mealtimes, bolus doses of insulin can be precisely calculated based on your current blood glucose level, insulin already in your system and the amount of carbohydrate you eat.
Basal insulin can also be adjusted to match activity levels, or if illness, stress or menstruation might be affecting your blood glucose. You can also use a bolus dose to help bring high blood glucose in range.
Connecting to the pump
The pump holds a cartridge of insulin and is connected to your body by flexible tubing. The tubing connects to an infusion set—a small needle, or cannula, that is held in place by a small plastic housing and adhesive. Cannulas can be made of flexible material or stainless steel, come in different lengths, and are inserted at various angles, to suit different body types and personal preferences.
Cannula and pump placement
The cannula can be inserted where it won't interfere with your clothes or daily activities, such as your abdomen, thigh or buttocks, and can generally stay in place for 2 or 3 days before it needs to be changed.
The pump itself can be worn on your waistband, or tucked in a pocket or bra. You can even buy special wraps that fit on your thigh or upper arm, to keep the pump under your clothes.