Accuracy of point-of-care capillary blood sugar measurements in critically ill patients: An observational study

Accurately monitoring blood glucose levels is vital for critically ill individuals. Point-of-care (POC) glucose meters are commonly used in local intensive care units (ICUs). This study aimed to assess the precision of POC glucose meter readings in critically ill individuals with specific evaluation in patients with and without shock against the reference standard of venous blood glucose measurements.

An observational study was done on adult patients admitted in the ICU at a teaching institution. Capillary blood samples were collected from the patient's fingertip using lancet device with aseptic measures. The sample was analyzed using the GlucoCare Sense Glucometer (RMD Mediaids Limited, Taiwan). At the same time, 2 ml of blood was drawn from the patient's peripheral veins and analyzed by glucose oxidase-peroxidase method as reference.

POC glucose measurements averaged 140 ± 20.23 mg/dl, while laboratory values were recorded as 116.10 ± 17.13 mg/dl. The difference between the two methods was 24.34 ± 12.01 mg/dl. A strong correlation (r = 0.805) was found between capillary and laboratory blood glucose levels, indicating a significant association (P < 0.0001). Twenty-two (44%) patients were in shock during the study. The mean difference between laboratory and POC blood glucose levels was higher in patients with circulatory shock (36.82 ± 4.84 mg/dl) than those without shock (14.61 ± 4.49 mg/dl), P < 0.05.

POC glucose meters may lead to underdetection of hypoglycemia in critically ill patients, as their values are higher than laboratory values. Moreover, the results showed that POC glucometers are inaccurate for monitoring glucose in hypotensive patients in shock. Standard venous glucose monitoring methods may be more appropriate for these patients.