Accuracy of Self-Monitoring of Blood Glucose: Impact on Diabetes Management Decisions During Pregnancy

PURPOSE: This study tested the hypothesis that the accuracy of self-monitoring of blood glucose (SMBG) values of patients with diabetes during pregnancy deviates substantially from reference values. METHODS: The patients' glucose values were measured on 6 different SMBG meters; reference values were from the HemoCue B Glucose Analyzer. Over a 5-year period, 1973 comparisons between SMBG values and reference values were recorded during clinic visits and used for this study. Data were analyzed for percent of values that varied more than +/- 10.5% and +/- 15.5% from the reference value. Out-of-range data at each variance level were analyzed to determine the impact on medical management if decisions were based solely on SMBG values. RESULTS: One third of SMBG readings deviated significantly, which could adversely affect treatment for half of these patients if diabetes management was based on SMBG values. At the 10.5% deviation level, 34% of SMBG meter readings were out of range; 54% of these would have implied erroneous treatment. At the 15.5% deviation level, 18% were out of range; 63% of these would have implied erroneous management. CONCLUSIONS: The accuracy of home meters should be verified at regular intervals, and SMBG values should not be the sole criterion for diabetes management during pregnancy.