Effects of pH on glucose measurements with handheld glucose meters and a portable glucose analyzer for point-of-care testing

Objectives. - To determine pH effects on glucose measurements obtained with the latest generation of glucose devices, to quantitate changes in glucose measurements obtained over a wide pH range, and to assess the potential clinical risks of pH effects with use of point-of-care glucose testing. Design. - Paired differences of glucose measurements between pH- altered and parallel control samples with target pH 7.40 were calculated. Setting. - A pH range of 6.94 to 7.84 was used to evaluate pH effects on glucose measurements in vitro with 6 handheld glucose meters and a portable glucose analyzer at both normal, 4.81 mmol/L (86.6 mg/dL), and high, 11.16 mmol/L (201 mg/dL), glucose levels. Main Outcome Measures. - Glucose measurements obtained from test samples and control samples were compared by calculating paired differences, which were plotted against pH to show pH effects on glucose meter measurements. Results. - At the normal glucose level, different pH levels did not interfere significantly with glucose measurements. At the high glucose level, a trend whereby low pH decreased and high pH increased glucose measurements was observed on the Precision G and the Precision QID glucose meters. Conclusion. - Because of potential risk in diabetic patients with ketoacidosis and in other patients with acid-base disorders, we recommend that clinicians choose glucose devices carefully and interpret the measurements cautiously when point-of-care glucose testing is performed in critically ill patients with acidemia, alkalemia, or changing acid-base status.