The exponential rise in the use of immune checkpoint inhibitors (Ipilimumab, Nivolumab, Pembrolizumab, Atezolizumab, Durvalumab, and Avelumab) as the new standard for cancer treatment increase the incidence the immune-related adverse events due to immune activation. Endocrine immune-related adverse events are the third most commonly reported. Thyroid gland is most susceptible to autoimmune dysfunctions from immune checkpoint inhibitors and associated with the use of anti-PD-1 monoclonal antibodies. Hypophysitis develops more often during therapy with anti-CTLA-4 monoclonal antibodies. But such immune-related adverse events as diabetes mellitus, hypoparathyroidism are rare (about 1% of cases).We present a clinical case of the patient with skin melanoma who was prescribed therapy with immune checkpoints inhibitors (Pembrolizumab). Immune-related adverse events developed with damage to the endocrine organs after 3 Pembrolizumab injections. Of greatest interest is the development of two endocrine immune-related adverse events at once: destructive thyroiditis (with a short phase of thyrotoxicosis and subsequent persistent hypothyroidism) and diabetes mellitus. We tried to reflect the chronology of diseases and their features as fully as possible for endocrinologists, oncologists, therapists, family doctors and other medical doctors of related specialties.