What is POC (Point-of-Care) glucose?

What is POC Glucose?

POC (Point-of-Care) glucose refers to bedside blood glucose testing performed using FDA-approved hospital-calibrated glucose meters that measure capillary blood glucose levels from fingersticks, providing rapid results to guide immediate clinical decisions in hospitalized patients. 1

Definition and Purpose

POC glucose monitoring is the standard method for hospital glucose surveillance, performed at the patient's bedside rather than in a central laboratory. 1 The testing uses portable glucose meters similar to those used by outpatients for home monitoring, but must meet stricter FDA standards for hospital use. 1

How POC Glucose Testing Works

• Sample collection: Capillary blood is obtained via fingerstick using lancets (which must never be shared between patients due to blood-borne pathogen risk). 1
• Measurement method: Hospital-calibrated POC meters analyze the blood sample and provide results within seconds to minutes. 1, 2
• Result documentation: POC results should be connected to electronic health records to enable real-time monitoring and audit capabilities. 2

Clinical Applications and Timing

For patients who are eating:

• POC glucose should be checked immediately before each meal to guide prandial insulin dosing. 1

For NPO (nothing by mouth) patients:

• Check POC glucose every 4-6 hours when patients are not eating or have poor oral intake. 1, 3

For patients on intravenous insulin:

• More frequent monitoring every 30 minutes to 2 hours is mandatory for safe insulin infusion management. 1, 3

Important Limitations and Accuracy Concerns

POC glucose meters are not as accurate or precise as central laboratory glucose analyzers, and clinicians must understand when results may be unreliable. 1

Factors that compromise POC accuracy:

• Poor perfusion (shock, hypotension, peripheral vascular disease). 1
• Edema at the sampling site. 1
• Anemia or erythrocytosis (abnormal hematocrit levels). 1, 4
• Certain medications commonly used in hospitals. 1
• Critical illness where capillary blood may not correlate with central venous glucose. 5, 6, 4

Critical safety rule:

Any POC glucose result that does not correlate with the patient's clinical status must be confirmed by measuring a serum sample in the central clinical laboratory. 1, 7

POC vs. Continuous Glucose Monitoring (CGM)

While CGM measures interstitial glucose continuously and can detect hypoglycemia more effectively than POC testing, CGM has not been FDA-approved for inpatient insulin dosing decisions. 1 During the COVID-19 pandemic, many hospitals used CGM under FDA enforcement discretion, but confirmatory POC capillary glucose testing remains recommended for insulin dosing and hypoglycemia assessment. 1

Quality Assurance Requirements

• Hospitals must use FDA-approved POC glucose monitoring systems specifically calibrated for hospital use, not consumer-grade meters. 1
• Careful analysis of device performance and reliability with ongoing quality assessments is critically important. 1
• Proper preparation of test sites, patient identification, and documentation are essential to avoid pre-analytical, analytical, and post-analytical errors. 5, 2

Common Pitfalls to Avoid

• Do not use fingerstick POC glucose in critically ill patients with poor perfusion without laboratory confirmation, as severe underestimation can occur. 6, 4
• Do not share lancets or fingerstick devices between patients due to blood-borne pathogen transmission risk. 1
• Do not accept discordant POC results at face value—always verify with laboratory testing when results don't match clinical presentation. 1, 7
• Do not extend monitoring intervals beyond 6 hours in NPO patients, even if glucose appears stable, as this increases undetected hypoglycemia risk. 3