PRL and diabetes mellitus: Another explanation is that prolactin plays a significant role in humoral immunity by binding to prolactin receptors on B-lymphocytes to stimulate the synthesis of immunoglobulins, and since the concentrations of prolactin are reduced in birthing parents with diabetes, this can impair the secretion of immunoglobulins (Smilowitz et al., 2013, Russell et al., 1985).