Effects of pH on Glucose Measurements With Handheld Glucose Meters and a Portable Glucose Analyzer for Point-of-Care Testing

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Abstract
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.