Autoimmune polyglandular syndrome type 2 (APS 2) is defined by the presence of Addison's disease (AD) associated with autoimmune thyroid disease and/or Type 1 diabetes mellitus (T1DM). It is a rare disease, affecting about 1.4-2 cases/100,000 inhabitants. Its less frequent clinical presentation is the combination of AD, Graves' disease, and T1DM. We present the case of a 42-year-old woman with a history of total thyroidectomy due to Graves' disease, type 2 diabetes mellitus, and hypertension, who sought the ED due to asthenia, dizziness, nausea, and vomiting. She reported having stopped antihypertensive therapy due to hypotension and presented a glycemic record with frequent hypoglycemia. On physical examination, she had cutaneous hyperpigmentation. She had no leukocytosis, anemia, hypoglycemia, hyponatremia or hyperkalemia, and a negative PCR. Serum cortisol <0.5 ug/dl (4,3-22,4), urine free cortisol 9 ug/24h (28-214), ACTH 1384 pg/mL (4,7-48,8), aldosterone and renin in erect position of 0 pg/ml (41-323) and 430.7 uUI/ml (4.4-46.1) respectively. Quantiferon TB was negative; computerized axial tomography of the adrenals showed no infiltrations, hemorrhage, or masses. The 21-hydroxylase antibody assay was positive. B12 vitamin was normal, anti-GAD antibodies were positive, anti-insulin, anti-IA2, and anti-transglutaminase antibodies were all negative. The patient started insulin therapy and treatment for AD with prednisolone and fludrocortisone with good clinical response. This case aims to alert to the need for high clinical suspicion in the diagnosis of AD. Since this is a rare autoimmune disease, it is important to screen for other autoimmune diseases in order to exclude APS.