An insulin pump is a compact, pager-sized, computerized device that can be worn on a belt. It is connected to the body via a flexible plastic tube through which insulin is delivered. The pump releases insulin in a steady, continuous background or "basal" dose, but also allows the wearer to add an additional dose, or "bolus" of insulin when needed, such as before a meal or snack.
"It provides more stable insulin deliveries and smoothes out glucose fluctuation compared with injections," explains Howard A. Wolpert, MD, senior physician and director of the insulin pump program at the Joslin Diabetes Center in Boston, in an interview with WebMD. "I think the advantage from a lifestyle standpoint is what attracts many people, because it does allow people much more flexibility in terms of eating times."
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Although people with diabetes can now use an ultra long-lasting insulin (insulin glargine) that releases an even basal dose for 24 hours after injection, Wolpert notes that "with glargine people still need to take multiple injections whenever they're going out to eat or whenever they're going to have a snack. With a pump it's much more convenient in terms of just having to press a button and get insulin delivered. For people eating out, if they're not certain what they're going to be eating they can take an initial bolus or pulse of insulin, and as the meal proceeds they can take further insulin depending on their [food] intake."
The pump also can help control the release of glucose during exercise, Wolpert says. Insulin levels normally drop during exercise to allow the release of stored glucose for use by the exercising muscles, but people who inject insulin may find it hard to predict how much insulin to have on board prior to exercise. In contrast, those who use pumps can more easily adjust the dose to their body's minute-to-minute-demands. "For the motivated patient who wants to lose weight through exercise, one can do it much more effectively if one's on a pump than say on insulin injection," Wolpert tells WebMD.
But while the insulin pump is for many people an improvement over multiple daily injections, it requires a dedicated and savvy operator to make it work. The user still has to perform multiple daily blood tests to check for glucose levels, and must know how to program in the right insulin dose after each test; currently available pumps can neither sense current glucose levels nor can they automatically adjust insulin levels.
"It's just a different tool for delivering insulin; the person still needs to input the doses, and to get the most out of the pump one still has to be pretty knowledgeable and skilled in diabetes self-management. It's not a tool for the novice," Wolpert says.
"It isn't right for everyone," agrees Michael Freemark, MD, professor of pediatrics and chief of the endocrine and diabetes division at Duke University Medical Center in Durham, N.C. "It requires a strongly committed family and an experienced diabetes team."
You're Never Too Young...
"If you have a very conscientious, careful, reliable family who's willing to monitor the use of the pump closely, I think in many ways that pump therapy is more effective in very young children than it is in teenagers who are out on their own and entirely responsible for their care independent of their parents," he says.
Freemark and colleagues performed a small pilot study of insulin pumps in young children, and found that the pumps reduced the number of episodes of severe hypoglycemia (abnormally low blood sugar) by a factor of five compared with insulin injections. The parents, when interviewed by the researchers, expressed greater confidence in their ability to manage their children's diabetes and a general improvement in the family's quality of life.
Insulin pumps may be particularly beneficial for children because their unpredictable food intake and energy expenditure make it difficult for parents to judge how much insulin they should give by injection ahead of time. In addition, because their small bodies require only fractions of adult insulin doses, "it's almost impossible to do it accurately through injections. I would venture to say that it isn't possible to administer quarter of half units of insulin accurately by insulin syringes," Freemark says.
Insulin pumps also are far less likely to cause episodes of severe hypoglycemia because they release insulin in a steady dose rather than in a major bolus, he adds.
"To my amazement, we have had no trouble with the children themselves," Freemark tells WebMD." We haven't limited their activities and they still do somersaults on the ground and wrestle with their brothers and sisters, but we haven't had the problem I was most worried about when we started, which was that the kid was going to pull the pump out, and play with it, and push the buttons - we've had none of that."
...Or Too Old
On the other end of the spectrum, many seniors with type 1 diabetes can also benefit from the use of an insulin pump. According to an American Diabetes Association publication, many seniors who use the pump report better control of complications, improved vision, better sleep, and relief from anxiety about hypoglycemia.
Insulin pumps cost several thousand dollars, but Medicare now covers the cost of pumps for many seniors, and other insurance plans also pick up some or all of the cost for their patients with diabetes, Freemark notes.