A Perspective on the Accuracy of Blood Glucose Meters During Pregnancy

Blood glucose monitoring is fundamental for hyperglycemia management during pregnancy, but are the devices up to the job? Studies assessing the accuracy of 10 commercially available glucose meters during pregnancy showed that although >98-99% of the meter values were in the acceptable zones of the error grid for the majority of the meters, the meter performance varied, with the majority showing positive bias and a few showing minimal negative bias. The mean difference between meter and laboratory plasma values varied between -0.33 and 0.73 mmol/L. Three meters showed deviations from laboratory results with a change in maternal hematocrit levels. No meters had a total analytical error <5%, and no studies evaluated meters using recent International Organization for Standardization 15197:2013 criteria. The Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT) recently showed that an antenatal continuous glucose monitoring system (CGMS), as an adjunct to capillary monitoring, was associated with a lower incidence of large-for-gestational-age babies, fewer neonatal intensive care unit admissions (>24 h), and a lower incidence of neonatal hypoglycemia. The flash glucose monitoring system shows good accuracy in pregnant women but has not been marketed widely in the U.S. We suggest that meters cannot be assumed to be sufficiently accurate during pregnancy and that manufacturers should ensure a total error <5%, with bias and imprecision <2% during pregnancy. Large studies are needed to evaluate the usefulness of CGMS among pregnant women with type 2 diabetes and gestational diabetes mellitus.