This is a prospective longitudinal study to study the agreement between a continuous glucose monitoring system (CGMS) versus current blood glucose monitoring. Subjects in this study will have their blood glucose measured regularly every 1-3 hours with current methods in the Cardiovascular Intensive Care Unit (CVICU), and by Point of Care (POC) fingerstick glucose using the Accucheck Inform II on the regular floors, and the CGMS reading at the same time will be captured. Subjects will have measurements taken throughout their stay in the CVICU and on the regular floors. Agreement and correlation between systems, as well as errors, will be calculated.

The Dexcom G7 will be placed either by an anesthesiologist or nurse anesthetist, or critical care physician, nurse or nurse manager upon arrival to CVICU, post cardiac surgery.

Standard of care:

Accuchek will be done per standard of care for post operative patients that are in ICU

Inclusion Criteria:

• Age 18 years old and above
• Planned cardiothoracic surgery
• Planned admission to Cleveland Clinic Main Campus building J5 or J6 or Q5 cardiovascular intensive care unit (CVICU) followed by transfer to the step down unit
• With or without known diabetes (as 75% of patients entering the CVICU have hyperglycemia requiring intravenous insulin infusion)
• If with known diagnosis of diabetes, diabetes can be type 1, type 2, or secondary (such as due to glucocorticoids or pancreatitis

Exclusion Criteria:

• Allergy to the material of the continuous glucose monitoring systems (CGMS) or the adhesive to be used
• Skin conditions precluding the use of the CGMS
• Pregnancy
• Other conditions that the investigators deem inappropriate for the study
• Patients receiving mechanical circulatory assist devices

The study will involve using blinded Dexcom G7 continuous glucose monitoring (CGM) devices