Objectives: (a). To describe the glucose content of normal human airways secretions; (b). to observe the effects of hyperglycemia and airways inflammation on airways glucose.
Design: Observational studies.
Settings: (a). St George's Hospital Medical School; (b). diabetes mellitus outpatient clinics; (c). adult general intensive care unit.
Patients: Nineteen healthy volunteers, 24 volunteers with acute rhinitis, 20 patients with diabetes mellitus, and 60 patients admitted to a general adult intensive care unit.
Measurements: (a). Non-ventilated patients: simultaneous measurement of blood and nasal glucose concentrations; (b). ICU patients: simultaneous blood, nasal, and endotracheal (ET) glucose concentrations.
Results: Nasal glucose was undetectable in all healthy volunteers. Glucose was detected in 12/24 volunteers with acute viral rhinitis [1 (1-2) mmol l(-1)] and 18/20 people with diabetes [4 (2-7) mmol l(-1)]. Glucose was detected in the ET secretions of 31/60 ventilated patients on ICU. Patients with ET glucose had significantly higher blood glucose (9.8+/-0.4 mmol l(-1)) than patients without ET glucose (7.2+/-0.3 mmol l(-1), P<0.001), and all patients with blood glucose >10.1 mmol l(-1) had glucose in ET secretions. Enteral nutrition did not affect the presence or concentration of glucose in ET secretions.
Conclusions: Glucose is not normally present in airways secretions, but appears where hyperglycaemia or epithelial inflammation occur. The detection of glucose cannot reliably be used to detect enteral feed aspiration.