The purpose of the study is to assess the performance of a new subcutaneous glucose sensor over a seven-day sensor life when used with currently marketed Medtronic Diabetes devices. In addition performance will be calculated for use of the new sensor with proposed new devices using new calibration algorithms.

The first generation Medtronic MiniMed Subcutaneous Glucose Sensor (Sof-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 was used as part of subsequent continuous glucose monitoring (CGM) systems, such as the Guardian REAL-Time and Paradigm REAL-Time sensor augmented insulin pump. The current configuration of sensor has undergone in vitro and in vivo testing. A new second-generation glucose sensor (herein referred to as the Comfort Sensor) has been developed. The first-generation glucose sensor was approved with reported sensor accuracy (MAD) of 18%; it was labeled for a maximum use duration of 72 hours, using only the abdomen as an insertion site. The new sensor is shorter and has a smaller diameter, with a smaller gauge introducer needle. The new sensor inserter is designed to be used with the new sensor. The objectives of this study are to 1) Assess performance of the Comfort Sensor when used over a period of seven days with currently available devices, and 2) Assess performance of the Comfort Sensor when used over a period of seven days using new calibration algorithms (post-processed with algorithm for future devices). Accuracy data will be calculated based on comparing calibrated glucose sensor values to a "gold standard" (YSI plasma glucose values) in adult subjects during in-clinic testing, and on comparing calibrated glucose sensor values to glucose meter values during in-home testing. The devices that will be used for gathering sensor data during this study will be: 1) the Comfort Sensor, 2) the MiniLink (Transmitter), 3) the Guardian REAL-Time Display Device and 4) the CGMS iPro.

Inclusion Criteria:

1. Males and females aged 18 through 75 inclusive
2. Diagnosed with Type 1 or type 2 Diabetes Mellitus, using insulin to treat their diabetes (Each site's and overall study enrollment of subjects with Type 2 diabetes will target 20% of the total number)
3. Willingness to perform required study and data collection procedures and to adhere to operating requirements of the Guardian REAL-TIME and CGMS iPro Systems
4. Willingness to perform at least 4 capillary blood glucose tests per day while wearing the Guardian REAL-TIME and CGMS iPro Systems
5. Willingness to participate in a 10 hour frequent blood sampling session during the study
6. Subject agrees to comply with the study protocol requirements
7. Informed Consent, HIPAA Authorization, and California Experimental Subject Bill of Rights (if applicable) signed by the subject
8. The Subject is willing to wear both the Guardian REAL-Time and CGMS iPro Systems for 14 days (~340 hours)

Exclusion Criteria:

1. The Subject has a history of tape allergies that have not been resolved
2. 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
3. Any additional condition(s) that in the Investigator's opinion would warrant exclusion from the study or prevent the Subject from completing the study
4. Subject is currently participating in an investigational study (drug or device)