INS and type 1 diabetes mellitus: These diseases clinically present in a similar way, with ongoing target cell destruction going unnoticed by the patient (largely asymptomatic), with symptoms appearing only after the loss of target cell function, such as pigment loss in vitiligo, insulin loss leading to ketoacidosis in T1D, loss of thyroid hormone and associated symptoms in Hashimoto’s thyroiditis, lack of intrinsic factor for B12 absorption in pernicious anemia, and loss of adrenal hormones leading to disrupted homeostasis in Addison’s disease.