Determining the Accuracy of Continuous Glucose Monitoring During Periods of Acute Glycemic Variability in Pregnancy

Background: The use of continuous glucose monitoring (CGM) in inpatient settings is highly attractive; it reduces the capillary glucose checks and enables remote monitoring. CGM systems have proven reliable in outpatient care; however, their reliability in hospitalized patients, particularly pregnant women, remains uncertain. Aim: To determine CGM accuracy and potential clinical risk of using CGM in pregnant women with type 1 diabetes mellitus (T1DM) or type-2 diabetes mellitus (T2DM) during acute hospitalization. Method: Prospective cohort study. CGM glucose was compared with paired capillary glucose readings as the reference. Concordance was assessed using mean absolute relative difference (MARD), the Food and Drug Administration standards for new integrated-CGM (iCGM) accuracy, and the diabetes technology society (DTS) error grid. Results: The dataset consisted of 1351 paired-readings from 26 women with T1DM and 11 women with T2DM. MARD was 12.9% overall, and 11.9% when the capillary glucose was 3.9–10.0 mmol/L. DTS error grid showed 81.6% of paired readings in zone A, 17.2% in zone B,1% in zone C and 0.1% in zone D. When capillary glucose was 3.9–10.0 mmol/L, 83.8% were in zone A, 15.5% in zone B, 0.6% in zone C, and 0.1% in zone D. Conclusions: These findings showed comparable accuracy in inpatient pregnant women to other inpatient groups in recent studies. CGM readings were highly correlated with the reference readings when capillary glucose was 3.9–10.0 mmol/L or when the CGM readings were 5.0–7.0 mmol/L. However, while CGM may guide inpatient antenatal diabetes care, critical management decisions (particularly around hypoglycemia) should be based on capillary glucose until greater concordance is established.