Abstract: A novel therapy for Pseudomonas aeruginosa infections, in particular in cystic fibrosis patients, is described. Macrophages provide the first line of defence in protecting the lung against bacterial infections. Nonetheless, Pseudomonas aeruginosa infections continue to be problematic in cystic fibrosis patients and are the leading cause of death in these patients. Previously, little was known regarding the factors which regulate the capacity of macrophages to mediate phagocytosis of Pseudomonas aeruginosa. The inventors have now shown that phagocytosis of nonopsonized Pseudomonas aeruginosa by macrophages is dependent upon the presence of glucose. They have also shown that the action of glucose is on the macrophage rather than the bacteria. Glucose therapy can therefore be used to prevent or combat Pseudomonas aeruginosa infections.