An insulin pump is a computerised insulin delivery device (that looks like a mobile phone) attached to the wearer by a length of clear plastic tubing (an infusion set) connected to a cannula inserted under the skin. The pump can be kept in your pocket, clipped to your waistband, or tucked into a sock or bra.
The best way to manage insulin-dependent diabetes is to imitate how the non-diabetic body regulates glucose.
What ever way insulin is given, it has to
a) provide enough basal insulin;
b) cover glucose levels in response to meals; and
c) reduce glucose levels to a normal range.
a) To meet the background or basal insulin needs of the body. In a person without insulin-dependent diabetes, the pancreas releases small amounts of insulin like a dripping tap. Basal insulin controls the release of stored glucose from the liver and regulates release of free fatty acids. In people with insulin-dependent diabetes who are not on the pump, basal insulin is replaced by one or two injections of long-acting insulin every day.
To replace basal insulin, the pump regularly delivers preprogrammed doses of fast acting insulin. The basal insulin delivery rates are programmed by you, in consultation with your diabetes care team. The rates will vary according to the time of day and your needs -you can programme less insulin at night for example, and adjust basal rates for a short time or reset them completely. All this is carried out at home without visiting a doctor or DSN. Basal levels of insulin can be reduced during exercise when you need less, and increased during illness or stress, when you need more.
b) To control blood glucose levels in response to meals. In a non-diabetic person, the pancreas releases a bolus of insulin to help the body derive energy from food and drink and reserve energy for later, for instance between meals or overnight. In people who are injecting insulin , this bolus is replaced by a mealtime injection of rapid-acting insulin to lower blood glucose level to a normal range.
With a pump, you programme the pump to deliver a bolus when you eat. Bolus amounts depend on: 1) the current blood glucose level; 2) the amount and type of food you intend to eat; 3) the amount of exercise likely within the next few hours. You will receive training and support from your diabetes care team to help you determine these insulin doses.
c) As with mealtimes, the pump can be instructed to give a bolus to bring a high blood glucose level back into range.
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