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.

Insulin pumps are machines, and anyone who's ever been in a car that didn't start knows that machines don't always work right. Being in a car that doesn't start is merely annoying; depending on an insulin pump that's not delivering insulin is a lot more serious. In the past, people using an insulin pump also needed to use a blood glucose monitor to insure that their pump was functioning properly. Newer insulin pumps contain a built in sensor, allowing for an automatic check on the pump's functioning.

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.

The study suggests that insulin pumps can be more effective than insulin injections. But insulin pumps do have disadvantages: they're expensive, need to be worn most of the time and require training to use properly. However, according to the American Diabetes Association website, most users agree that their advantages outweigh the disadvantages.

More specific information on insulin pumps and how they work can be found at the American Diabetes Association's home page,, 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.