Agreement Between Fingerstick Blood Glucose and Continuous Glucose Monitor Measures Among Long-Term Care Facility...

Long-term care facility (LTCF) residents with diabetes are at high risk of hypoglycemia. Continuous glucose monitoring (CGM), which measures interstitial glucose at 5-min intervals over 10-14 days, and fingerstick blood glucose (FBG) which analyzes glucose from a drop of blood, are both used to monitor glucose levels. Observational studies using electronic health record (EHR) data containing FBG measures could help to identify ways to reduce hypoglycemia risk. We first need to understand the validity of such data. Our objective was to compare EHR-based FBG measures against reference-standard CGM measures of hypoglycemia.

We studied two cohorts of residents with diabetes in parallel. In Cohort 1, we analyzed linked CGM and Long-Term Care Data Cooperative EHR-based FBG data collected in 2023. In Cohort 2, we analyzed linked CGM and EHR-based FBG data obtained directly from LTCFs between 2022 and 2023. We defined hypoglycemia as glucose < 70 mg/dL and assessed the sensitivity and specificity of FBG versus CGM measures to detect hypoglycemia. The unit of analysis was each pair of contemporaneous FBG-CGM measures.

In Cohort 1, two White female residents with a mean (standard deviation [SD]) age of 81 [12.7] years generated 25 daily hypoglycemia measurements. The sensitivity and specificity were 14% and 100%, respectively, for FBG-measured hypoglycemia. Cohort 2 included 40 residents (mean [SD] age 68 [11] years, 45% females, 60% White race) who generated 425 daily measurements of hypoglycemia. The sensitivity and specificity were 13% and 99%, respectively.

EHR FBG measures of hypoglycemia had high specificity but failed to identify four out of every five hypoglycemic events among LTCF residents. Researchers and healthcare providers should assume hypoglycemia is measured with substantial errors in EHRs and account for this in their research and clinical practice.