Assuring the accuracy of home glucose monitoring

An estimated 2.5 million diabetic patients in the United States practice self-monitoring of blood glucose (SMBG). The validity of the glucose values they obtain is in doubt. An American Diabetes Association consensus panel reported that up to 50% of SMBG determinations might vary more than 20% from their true value. Accurate glucose values are an integral part of intensive treatment and reduction of long-term complications. The objective of this study was to determine the technical skill and accuracy of SMBG in an outpatient population.

This study was conducted in two family practice residency sites where 111 patients with type 1 and type 2 adult diabetes were observed testing their blood glucose values on their own glucose monitors. Patient-measured glucose levels were immediately compared with a laboratory value obtained from a calibrated hand-held glucose monitor.

Fifty-three percent of patient glucose values were within 10% of the control value, 84% were within 20% of the control value, and 16% varied 20% or more from the control value. Two patients had dangerously inaccurate glucose determinations. Four glucose monitors required replacement. The patients were observed using a 13-point checklist of critical steps in calibration and operation of their glucose monitor. Only 1 patient made no errors in testing.

Despite multiple technical errors when using SMBG, most patients obtained clinically useful values. This project can be easily introduced into a medical office.