The purpose of this study is to assess the performance of the subcutaneous glucose sensor over an extended sensor life. The sensor is currently approved for 3 days of use and this study will examine sensor safety and accuracy when used for six days. This study will also test sensor safety and accuracy when inserted in an alternate body location (buttock area in addition to abdomen area). The study hypothesis is that the sensor performance will not greatly diminish when used for six days, or in an alternate insertion area.

The Medtronic MiniMed Subcutaneous Glucose Sensor was originally approved by the FDA for commercialization as part of the Continuous Glucose Monitoring System (CGMS) on June 15, 1999 (PMA 980022). The Sensor is composed of a microelectrode with a thin coating of glucose oxidase beneath several layers of biocompatible membrane. This same sensor is used as part of the Guardian REAL-Time System, the latest advance in continuous glucose monitoring, which is based on the CGMS. Similar to the CGMS, the Guardian REAL-Time System has been developed for use in conjunction with a standard home blood glucose meter. The Guardian REAL-Time received regulatory approval from the FDA in 2006.

As currently used, the Subcutaneous Glucose Sensor is labeled for a maximum use duration of 72 hours, using only the abdomen area as an insertion site. Recent studies have shown that the useful sensor life could extend beyond three days, and it is reasonable to expect a significant percentage of sensors to last six days. It is the goal of this study to confirm sensor performance accuracy data from one of these recent studies. The sensor is also commonly worn in body areas other than the abdomen (such as the buttock). This study will also demonstrate sensor accuracy when used in an alternate site.

Inclusion Criteria:

• Males and females aged 18 through 75 inclusive
• Type 1 Diabetes Mellitus treated using either CSII (continuous subcutaneous insulin infusion) or MDI (multiple daily injections) for a minimum of 3 months
• Willingness to perform required study and data collection procedures and adhere to operating requirements of the Guardian REAL-Time and CGMS iPro Systems
• Willingness to perform at least 4 capillary blood glucose tests per day while wearing the Guardian REAL-Time and iPro Systems
• Willing to participate in a 12 hour frequent blood sampling session during the study
• Subject agrees to comply with the study protocol requirements
• Informed Consent, HIPAA Authorization, and California Experimental Subject Bill of Rights (if applicable) signed by the subject
• The Subject is willing to wear both the Guardian REAL-Time and CGMS iPro Systems for 6 days (~144 hours).

Exclusion Criteria:

• The Subject has a history of tape allergies that have not been resolved
• The Subject has any skin abnormality (e.g. psoriasis, rash, staphylococcus infection) that has not been resolved and would inhibit them from wearing the sensors
• Any additional condition(s) that in the Investigator's opinion would warrant exclusion from the study or prevent the Subject from completing the study
• Subject is currently participating in an investigational study (drug or device)