Evaluation of a subcutaneous continuous glucose monitoring system in critically ill neonatal foals

Dysglycemia is common in critically ill neonatal foals. Continuous glucose monitoring systems (CGMS) are potentially useful in these cases, but factors such as poor peripheral perfusion could interfere with results.

Evaluate the correlation, agreement, and accuracy of CGMS compared to point-of-care glucometry (POCG) and laboratory analysis (LAB) in critically ill neonatal foals and assess the impact of hypotension on CGMS measurements.

Fifteen critically ill, client-owned neonatal foals.

In a prospective method comparison study utilizing clinical cases, glucose concentration was measured serially using CGMS and POCG (every 6 h), and LAB (every 24 h) for pairwise comparison. Blood pressure was measured every 12 h.

Average bias (95% limits of agreement) between CGMS and LAB, POCG and LAB, and CGMS and POCG were 48 mg/dL (-27 to 111), 10 mg/dL (-23 to 45), and 38 mg/dL (-21 to 98), respectively. Spearman's correlation was significant between CGMS and LAB (r = 0.65), POCG and LAB (r = 0.77), and CGMS and POCG (r = 0.75). The CGMS accuracy was low with only 15.5% of CGMS concentrations within 15% of LAB concentrations, compared with 88.3% for POCG. Hypotension did not affect CGMS measurements.

The CGMS provided glucose measurements above both LAB and POCG concentrations. Given its low correlation and accuracy, CGMS cannot replace LAB or POCG as the sole glucose measurement method in critically ill foals. However, it is a useful adjunct for tracking trends and providing alerts.