The airway epithelium is covered by a thin layer of surface liquid (ASL), which is vital for maintaining the sterility of the respiratory tract. The glucose concentration of the ASL (~0.4mM) is much lower than that in blood and is tightly regulated by the airway epithelium (1). ASL glucose is elevated in patients with cystic fibrosis (CF; ~2mM) and is associated with increased incidence of respiratory bacterial infection (2). The aim of this study was to compare the effect of P. aeruginosa on the mechanisms governing airway glucose homeostasis in polarized monolayers of CF and non-CF primary human bronchial epithelial (HBE) cells. In addition, Calu-3 monolayers were used to evaluate the potential importance of glucose on P. aeruginosa growth, in comparison to other hallmarks of the CF ASL, namely mucus hyper-viscosity and reduced bicarbonate content/acidic pH (3). The addition of P. aeruginosa filtrate to HBE monolayers reduced transepithelial resistance and was associated with an increase in paracellular permeability of glucose, as well as enhanced glucose-uptake. The increase in paracellular glucose flux was much greater across CF HBE monolayers (145±28%) compared to non-CF (56±23%, p<0.05, n=3) and was associated with elevated P. aeruginosa growth. No difference in glucose uptake was observed between non-CF and CF monolayers (p>0.05, n=4). Increasing the basolateral glucose concentration from 5 to 15mM resulted in a 54±12% increase in P. aeruginosa growth on the apical surface of HBE monolayers (p<0.05, n=3) and a 76±16% increase on Calu-3 monolayers (p<0.01, n=7), after 6 hours of co-culture. Removal of bicarbonate from the bathing solution (replaced with HEPES) led to elevated bacterial growth (by 109±7%, p<0.01, n=3) and the pH of the surface fluid was also more acidic (7.06±0.03 compared to 7.43±0.03 using bicarbonate; p<0.01, n=3). P. aeruginosa growth was significantly reduced by 57±18% following the addition of the cAMP-agonist forskolin (5µM, p<0.05, n=3) and this was associated with an alkalinisation in fluid pH to 7.51±0.01, (in bicarbonate-buffered solution; p<0.05). In both cases, elevating basolateral glucose increased apical bacterial growth. The presence of a thick mucus layer across Calu-3 monolayers also increased P. aeruginosa numbers by 84±13% (p<0.05, n=3). Similarly, under these conditions raising basolateral glucose enhanced the growth of the bacterium by 53±8% (p<0.05, n=3). These results indicate that P. aeruginosa induced an elevated glucose leak across the CF epithelium compared to non-CF. In addition, elevating glucose increased P. aeruginosa growth over and above the effects of pH/bicarbonate and mucus. Together these studies highlight the potential importance of glucose in promoting P. aeruginosa growth and respiratory infection in CF and CF-related diabetes.