Evaluate the usefulness of continuous glucose monitoring devices in terms of their ability to identify periods throughout the day when glucose varies significantly.

Many CGM systems use a surrogate for blood glucose--tissue glucose or interstitial glucose. Interstitial fluid (ISF) is the medium for these approaches. A physiological lag in ISF glucose relative to capillary blood glucose has been noted, probably due to relatively low blood perfusion at the sampling site. 9 This physiological lag can result in an accuracy error, manifesting as a significant bias between blood and tissue glucose, particularly during periods of rapid glucose change. This lag error might be particularly meaningful when glucose is rapidly dropping towards hypoglycemia.

Inclusion Criteria:

• adult
• A1c >7.4 within last 4 months
• type 1 or 2 diabetes treated with basal/bolus insulin

Exclusion Criteria:

• under 18 years of age
• unable to read/write english
• allergy to adhesives
• employee of CGM company

adults with diabetes who are treated with insulin