An Outpatient Pump Shutoff Pilot Feasibility and Safety Study

The purpose of this study is to evaluate an overnight system that will turn off the insulin pump automatically if the system predicts that a low blood sugar is likely. The study system includes a combination continuous glucose monitor (CGM)/ insulin pump made by Medtronic MiniMed, Inc and a regular laptop computer that runs a computer program that predicts low blood sugar. It works by (1) measuring the glucose levels under the skin with a continuous glucose monitor, (2) using a computer program on a laptop to predict what will happen to the glucose level over the next 35-55 minutes, and (3) turning off the insulin pump when the computer program predicts that low blood sugar will occur. We have tested this system overnight in the hospital and are ready to test the system in the home environment to learn more about how well it will work and to make sure that the blood sugar does not go too high when the pump shuts off. This study has several phases and will take about a month or a little more for a patient to complete. Patients will use the study system for about 5 days at home to show that the patient is able to use it correctly. After that, the patient will be asked to use the study system each night for an additional 3-4 weeks. During this time, the system will be active for two-thirds of the nights and not active for one-third of the nights. When the system is active and predicts that your blood sugar will become low, the insulin pump will shut off for up to 2 hours. The study will include 2 clinical centers in the United States.

Patients who meet all eligibility criteria will use the study system overnight at home for about 5 nights to demonstrate their ability to use the system and submit study data to the Coordinating Center. Patients who successfully demonstrate their ability to use the system as described above will be eligible for the randomized trial phase. This phase consists of use of the full system as an outpatient for approximately 21 nights: * Each night the blood glucose level will be checked with the study blood glucose (BG) meter and used to perform a calibration of the CGM. The calibration must occur no more than 90 minutes prior to activation of the system. NOTE: Patients will be instructed to calibrate the CGM per manufacturer guidelines. * Then the system will be activated, linking the CGM and insulin pump to the computer at the bedside. * A randomization schedule on the laptop will be used to determine whether the 'pump shut off' application will be active that night or not. * Patients will be blinded as to whether the pump shut off is active when a session is initiated each night. * There will not be an alarm if the pump shuts off. The CGM alarm will be set to 60 mg/dL. When a CGM alarm occurs, the patient will be asked to measure the blood glucose with a BG meter, if he/she is aware of the alarm. * The time period for outcome assessment each night will be from the time the system is activated until it is turned off in the morning. * Pump shut off, when it occurs, will be for up to 2 hours. Multiple instances of pump suspension can occur if there are recurrent predictions of hypoglycemia during the night. * Patients will be asked to check blood glucose with the study BG meter, blood ketones with the study ketone meter, and urine ketones with a ketone strip each morning prior to breakfast and enter the results on the study laptop. The patient will be instructed to contact the study physician if the blood glucose or ketone readings are out of an expected range. Patients will be contacted if these morning safety values are not reported as required or are out of range. * Patients will be asked to record all overnight carbohydrate intake on the study laptop. * Patients will be asked to perform periodic data uploads using the study laptop. Monitoring processes will ensure that the patient is contacted if these uploads do not occur as required, or if review of an upload reveals any extreme, prolonged episodes of low or high blood glucose readings, or elevated morning blood glucose, blood ketone, or urine ketone values. Upon completion of the study, patients as well as study clinicians will be asked to complete a questionnaire regarding use of the study system. There will a follow-up visit after completion of 21 successful nights of study system use. A successful night of study system use is defined as use of the system for at least four hours. Phone contacts with the patients will be made once a week.