Glucose concentration in the fluid that lines the lumen of human airways (~0.5mM) is normally lower than that of blood (5mM). This implies that glucose is actively transported out of the airway lumen. We have also shown that people with hyperglycaemia have increased glucose levels in airway secretions (1). However, it is not known how glucose is transported into or out of the human airway lumen. Glucose transporters can be divided into two groups: the facilitative glucose transporters (GLUTs), and the sodium-glucose co-transporters (SGLTs). The aim of this study was to assess the relative contribution of glucose transporters to glucose transport in polarised and non-polarised human bronchiolar epithelial H441 cells, maintained at 1, 5, 10 and 15 mM glucose overnight, using phloretin (GLUT inhibitor), phlorizin (SGLT inhibitor) and ouabain (Na⁺,K⁺-ATPase inhibitor). Functional transport studies were carried out over 10 min using ³H-glucose. In non-polarized cells glucose transport was preferentially via GLUTs, with phloretin inhibiting ∼90% of transport at all glucose concentrations (n = 6). Lowest levels of uptake were observed at 1 mM (18.4 ± 0.2 nmol glucose/mg protein), levels were raised at 5 and 10 mM (25.2 ± 0.2 and 26.5 ± 0.2 nmol glucose/mg protein, respectively) and maximal at 15 mM glucose (34.0 ± 1.6 nmol glucose/mg protein). We observed no ploridzin-inhibitable, SGLT-mediated glucose transport in non-polarised cells. Cells were polarised by growing as confluent monolayers at the air interface on permeable supports for 6-7 days. Under these conditions GLUT-mediated transport remained the principal mechanism of glucose uptake across both the basolateral and apical membrane. However, a significant SGLT-mediated transport component was observed across the basolateral membrane at all glucose concentrations studied (≥ 20%) and was also present across the apical membrane at 1 and 5 mM glucose. The effect of ouabain indicated that SGLT-mediated transport was coupled to the transmembrane Na⁺ gradient at 1 and 5 mM glucose but not at 10 and 15 mM glucose. Furthermore, in contrast to non-polarised cells, total transport across both apical and basolateral membranes of polarised cells was lower at 15 mM glucose (apical 6.6 ± 0.2; basolateral 18.1 ± 0.6 nmol glucose/mg protein) than at 10 mM glucose (apical 24.6 ± 1.4; basolateral 44.0 ± 1.2 nmol glucose/mg protein, p < 0.05, n = 6). These data indicate that both facilitative and active glucose transport systems are present in H441 lung epithelial cells and that both may have a role in transporting glucose out of the airway lumen. The process of cell polarisation induced SGLT-mediated glucose transport across apical and basolateral membranes. In addition, polarisation caused glucose uptake to be down-regulated when cells were subjected to 15mM glucose.