Effectiveness and Safety Study of the Dexcom G4™ Continuous Glucose Monitoring System

The purpose of this study is to evaluate the effectiveness and safety of the Dexcom G4 System when used as an adjuvant to blood glucose testing over a 7-day period in people \>18 years-old with diabetes mellitus.

The primary objective is to characterize the System performance with respect to laboratory reference venous sample measurements. The device performance will be primarily evaluated in terms of point and rate accuracy of the G4 System in reference to YSI.

Safety of the G4 System will be characterized by Adverse Device Effects and Serious Adverse Device Effects experienced by study participants.

The primary objective is to characterize the System performance with respect to laboratory reference venous sample measurements. The device performance will be primarily evaluated in terms of point and rate accuracy of the G4 System in reference to YSI. The trend accuracy of the device performance, i.e., continuous glucose error grid analysis, will be evaluated as well as the temporal G4 System accuracy at different glucose rates of changes and different glucose ranges (hypoglycemic, euglycemic, and hyperglycemic ranges). The primary matched paired (Sensor-YSI) measurements will be collected during multiple in-clinic days.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 years or older;
* Diagnosed with diabetes mellitus;
* Use one of the following for their diabetes management:

  * intensive insulin therapy (IIT) or
  * non-intensive insulin therapy (non-IIT)
* Intensive-insulin using (IIT) subjects only - During each in-clinic session, willing to have their blood glucose levels manipulated into high and low glucose levels. Subjects not on IIT will only be observed during each in-clinic session.
* For subjects that exercise routinely (at least 3 times per week), willing to exercise on each in-clinic session, if asked;
* Willing to take a minimum of 7 fingersticks per day during home use days;
* Willing to refrain from the use of acetaminophen during sensor wear period and the day prior to sensor insertion;

Exclusion Criteria:

* Have extensive skin changes/diseases that preclude wearing the required number of devices on normal skin (e.g., extensive psoriasis, recent burns or severe sunburn, extensive eczema, extensive scarring, extensive tattoos, dermatitis herpetiformis) at the proposed wear sites;
* Have a known allergy to medical-grade adhesives;
* Are pregnant as demonstrated by a positive pregnancy test within 72 hours of sensor insertion,
* Are on dialysis;
* Have a hematocrit that is less than 36% or greater than 55% at screening visit;
* Currently participating in another investigational study protocol (if a subject has recently completed participation in another drug study, the subject must have completed that study at least 30 days prior to being enrolled in this study);
* Have a history of cardiovascular disease (including, but not limited to ischemic heart disease, peripheral vascular disease, cardiomyopathy, cerebrovascular disease, congenital heart disease, or significant arrhythmias), epilepsy, severe migraines in the past 6 months, adrenal disease, syncope, significant hypoglycemia unawareness, or a history of severe hypoglycemia (requiring emergency medical intervention) within the last 6 months;
* Have any chronic infectious disease or intercurrent illness that would interfere with their participation in the study or pose an excessive risk to study staff handling venous or capillary blood samples (e.g. HIV/AIDS, Hepatitis B or C);
* Have a MRI scan, CT scan, or diathermy scheduled during the week of the study. If any of these procedures are required urgently during the study, subjects will notify the study staff, end their CGM session, and remove their sensor.