CD40LG and diabetes mellitus: However, a recent study revealed a link between low levels of peritoneal B-1a cells and low production of IgM in DM mice.28 Experiments in vitro have confirmed the causal relationship of high concentrations of glucose on reduced secretion of total IgM.28 Similar mechanisms may work to induce lower s-IgA secretion rates in human DM patients’ salivary glands.