The airway surface liquid (ASL), a protective layer secreted by the airway epithelium, represents the first line of defence against inhaled infectious material. It contains a complex array of proteins and peptides that aid the neutralisation and removal of inhaled microbes and toxicants. Diabetic hyperglycaemia has been associated with an increased susceptibility to acute lung infections. We hypothesised that diabetes does this by changing the state of the ASL proteome/peptidome. Therefore, we examined how hyperglycaemia changed the ASL peptide profile of BMI-transformed normal human bronchial epithelial cells (HBEC), cell-lines Calu3 (submucosal adenocarcinoma) and H441 (Clara cell like adenocarcinoma). ASL was acquired by washing the apical surface of epithelial monolayers grown at air:liquid interface with PBS (100ml) at 0, 24 and 120 hours after exposure to hyperglycaemic (25mM glucose) or normoglycaemic (5mM glucose and 20mM mannitol) basolateral medium. The ASL peptides < 10KDa, were subsequently isolated and analysed using the Q Exactive™ HF-X Hybrid Quadrupole-Orbitrap™ Mass Spectrometer. The resulting spectra of uncleaved peptides and their subsequent fragments were analysed using the pNovo sequencing tool. Our preliminary results identified 4765 unique peptides (NHBE-BMI1: 646, Calu3: 3150, H441: 1197). Of these, 37 peptides were common to all samples regardless of glycaemic state. Among these common peptides were several originating from histone and fibrinogen families, both of which are known to generate bioactive peptides. These common peptides were synthetically produced through SPOT synthesis and tested for antimicrobial activity. Histone H1.4 is a parent protein to several common peptides, our initial examination of its intracellular abundance showed a decrease in hyperglycaemic conditions. Alongside this an N-terminal H1.4 histone peptide has been identified through dot blotting in the ASL. Our aim is to test possible biologically relevant methods of activating these peptides to enable antimicrobial activity.