Insulin Pump With Glucose Sensor More Effective at Lowering HbA1c Than Multiple Daily Injections

Becky McCall

October 05, 2009

October 5, 2009 (Vienna, Austria) — A sensor-augmented pump (SAP), which combines an insulin pump with a continuous glucose sensor, delivers lower hemoglobin (Hb)A1c levels than multiple daily injections, without an increase in hypoglycemia. This finding potentially moves pumps a step nearer to the ultimate aim of a closed system and greater control and convenience for patients with type 1 diabetes, researchers reported here at the European Association for the Study of Diabetes 45th Annual Meeting.

Standard pumps provide the patient with a continuous infusion of short-acting insulins instead of multiple daily injection therapy, which provides a one-time, less flexible hit with long-acting insulin. The SAP combines a continuous glucose sensor with the insulin pump.

"By measuring glucose concentration in the subcutaneous tissue every 5 minutes, the patient has a constant stream of information, compared with patients without a sensor who have to measure glucose levels with a finger stick test at mealtimes and a few extra times during the day. Previously, patients only had 5 or 6 measurement time points, but now they know this level throughout the day," said Jeroen Hermanides, MD, from the Academic Medical Centre in Amsterdam, the Netherlands, who presented the study.

Coauthor J. Hans DeVries, MD, also from the Academic Medical Centre in Amsterdam, added: "We particularly wanted patients who had a problem with diabetes control to counteract the common belief that sensors are toys for boys, that many people use sensors for convenience but don't necessarily need them," he told Medscape Diabetes & Endocrinology.

The multinational, multicenter, randomized controlled trial involved 83 patients with type 1 diabetes. All patients had an HbA1c level above or equal to 8.2%. All received 26 weeks of therapy either with a SAP or with the standard of care, multiple daily injections. All patients had suboptimal control of HbA1c. Levels of HbA1c were measured at 13 and 26 weeks and the occurrence of hypoglycemic and hyperglycemic events was recorded. The duration of hyperglycemic events was also measured.

After 26 weeks of SAP therapy, the HBA1c decreased from 8.46 ± 0.95% to 7.23 ± 0.65%. In the multiple daily injection group, mean HbA1c was 8.59 ± 0.82% before therapy and 8.46 ± 1.04% after. "When we account for baseline HbA1c, there is a 1.21% magnitude of change compared with [multiple daily injection] therapy. But we also saw the duration of hyperglycemic events decrease. So there weren't fewer hyperglycemic events but they were of shorter duration. Hyperglycemia is corrected earlier than if the patient has to wait for the next finger prick," added Dr. Hermanides.

In addition to continuous monitoring, the SAP has a program called a Bolus Wizard, which provides the patient with advice on the required amount of insulin to cover a meal without the need for a finger prick test. Dr. DeVries explained: "We found SAP-controlled glucose levels were not accompanied by a significant increase in hypoglycemia. If you optimize insulin delivery by moving from injections to an insulin pump, and in addition optimize glucose levels with a continuous stream of glucose data and information from the Bolus Wizard, then this will make a difference to HbA1c levels."

Commenting on the use of insulin pumps, Dr. Denis Raccah, MD, diabetologist from the University Hospital Sainte Marguerite in Marseille, France, said the SAP was an important step toward developing a closed loop system and a significant advance for patients. "It is not a closed loop system yet because we do not have the algorithm between glycemia and insulin dose; it is still an open loop system. Patients have real-time access to their glycemia, thus avoiding hypoglycemic events during the night. Sometimes patients don't feel hypoglycemic during the night so this device could be used with an alarm. It would also prove useful in physical activity."

He continued to explain that in the REAL Trend study, which Dr. Raccah led, it was shown that when a poorly controlled patient on multiple daily injections is transferred to an integrated system with an insulin pump and sensor, rather than a pump with glucose measured conventionally, then a significant improvement in HbA1c is seen after 6 months, and there is no increase in hypoglycemic events compared with using a pump alone."

Simon Heller, MB, BChir, MRCP, DM, FRCP, from the Sheffield Teaching Hospitals NHS Foundation Trust in the United Kingdom, told Medscape Diabetes & Endocrinology that "the potential of sensor-augmented pump therapy to improve glycemic control without increasing the risk for hypoglycemia may be a significant advance, but further work is still needed."

"These benefits have also been reported with high-quality structured education alone," Dr. Heller pointed out. "Future trials need to include a structured education arm as a control to measure the additional benefit of the technology."

Dr. DeVries received funding from Medtronic. Dr. Raccah's Real Trend study was also funded by Medtronic. Dr. Heller has disclosed no relevant financial relationships.

European Association for the Study of Diabetes (EASD) 45th Annual Meeting: Abstract 90. Presented October 1, 2009.


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