In a one-year trial, patients with type 1 diabetes who used an insulin pump achieved better blood sugar control than patients who used the standard treatment of insulin injections. The pump used in the study contained a built-in blood glucose sensor, giving its users the ability to continuously monitor their blood sugar.
Type 1 diabetes is the less common form, where people produce no insulin or only tiny amounts of it.
Insulin pumps work by continuously delivering a low level of insulin. Larger amounts of insulin are delivered at mealtime, with the exact amount programmed by the user. This mimics the way the body naturally produces and delivers insulin more closely than insulin injections do.
All subjects had set a target of 7.0% or lower for A1C. One year into the study, 27% of the pump users met this target, compared to only 10% of the injection users.
In the study, 485 subjects with type 1 diabetes, age 7-70, used either the sensor-augmented pump or insulin injections for an entire year. Control of blood sugar level was estimated by A1C measurement. The amount of hemoglobin A1C in the blood rises when blood sugar is high and decreases when blood sugar lowers. For this reason, measuring A1C levels is a standard way of getting a picture of blood sugar control in patients known to have diabetes. Normal is roughly 4 to 5.9%; for controlled diabetes, the goal is under 7%.
The average A1C level of the study subjects was 8.3% at the start of the study. One year later, it was 7.5% for those who used the insulin pump and 8.1% for those who gave themselves insulin injections. All subjects had set a target of 7.0% or lower for A1C. One year into the study, 27% of the pump users met this target, compared to only 10% of the injection users.
The number of adverse events, such as episodes of severe hypoglycemia, was similar in both groups.
Just because an insulin pump contains a blood sugar sensor doesn't mean that owners will always use or pay close attention to the readings. The researchers found that the more often pump owners used the sensor, the lower their A1C level was, one year into the study. This is presumably because those who paid more attention to their blood sugar readings were able to adjust their insulin dose more precisely.
More specific information on insulin pumps and how they work can be found at the American Diabetes Association's home page, http://www.diabetes.org/, by searching the term "insulin pump."
An article detailing the study was published online by the New England Journal of Medicine on June 29, 2010.