Reliability of the Freestyle Libre CGM in the Inpatient Setting During the COVID-19 Surge

In hospitalized patients diagnosed with COVID-19, diabetes mellitus is associated with a higher mortality. Patients with controlled blood glucose have a lower mortality rate than those who are uncontrolled. However, a rigid blood glucose control - which may lead to hypoglycemia- is associated with higher mortality rates. Thus, adequate glucose monitoring is important for hospitalized diabetic patients.

Previous studies have shown that CGMS, in the outpatient setting, engender better glycemic control thereby reducing risk of hypoglycemia. CGMS offer a replacement for finger stick blood glucose monitoring which may not identify an incidence of hypoglycemia until symptoms drive the patient to test. Furthermore, finger stick blood glucose monitoring is painful and time consuming thus causing many patients to avoid this aspect of diabetes self-care management.

Freestyle Libre CGMs sample interstitial fluid glucose subcutaneously. Measurement frequencies typically range from 1 to 15 minutes and most commonly are every 5 minutes.

Previous studies in hospitalized patients living with diabetes mellitus on basal bolus regimen have shown:

• Use of the CGM increased detection of both hypoglycemic and hyperglycemic events versus those sensed by POCT.

One investigation identified 88 postprandial hyperglycemic excursions in patients with CGM use as opposed to 61 in those with POCT. Another noted that when comparing the CGM use with that of POCT, the former identified 55 hypoglycemic events whereas the latter only found 12.

• No difference in mean daily glucose CGM and POCT readings. In a study of 38 patients, the investigators noted no difference in mean daily glucose between the CGM and POCT.