Critical Limits and Clinical Recommendations for Notification of Life-Threatening Glucose Test Results in the 21st Century.

Abstract

Critical limits represent quantitative boundaries of life-threatening diagnostic results that demand urgent clinician notification and potentially, lifesaving intervention. To document 35-year changes in glucose critical limits, characterize decision thresholds at independent and network hospitals, identify US geographic risk differences, report point-of-care testing results, and align critical notifications, pathophysiological risk, and consensus recommendations to improve outcomes. We gathered critical limit notification lists from 417 hospitals comprising university, trauma, and heart centers, and network and community hospitals in all 50 states and Washington, District of Columbia, then extracted glucose critical limits for adults and newborns. All hospitals listed low and high glucose critical limits. Between 1990 and 2025, low glucose critical limits increased significantly (P < .001) with medians of 45 (range, 30-70) versus 50 (range, 35-60) mg/dL, respectively. Histograms documented striking inconsistencies. Matched pairs (N = 73) of laboratory versus point-of-care low glucose critical limits at the same hospitals did not differ significantly. A US risk level map identified geographic discrepancies relative to the neuroglycopenic impaired awareness threshold of 54 mg/dL. There were statistically significant changes in newborn low and high distributions with 2025 medians of 40 (range, 20-55) and 200 (range, 120-500) mg/dL, respectively. An increased median low critical limit of 50 mg/dL does not match the 54 mg/dL threshold for neuroglycopenic loss of awareness that places patients at risk. The median high critical limit of 450 mg/dL at network hospitals decreases the risks of extreme hyperglycemia. The risk map revealed geographic inconsistencies, lack of harmonization, and poor alignment with consensus clinical recommendations.