A 28-year-old man comes to the emergency department due to a 2-day history of polyuria, polydipsia, abdominal pain, nausea, and vomiting. He was diagnosed with primary adrenal insufficiency 6 months ago after developing fatigue and weight loss. The patient was started on hydrocortisone and fludrocortisone at that time, resulting in improvement of symptoms and return to baseline weight. Medical history is otherwise unremarkable. The patient's mother had Graves disease treated with radioiodine, and his sister has hypothyroidism. Family history is negative for diabetes mellitus. The patient does not use tobacco, drinks "a few beers on weekends," and used marijuana occasionally during college. Temperature is 36.9 C (98.4 F), blood pressure is 90/65 mm Hg, pulse is 115/min, and respirations are 22/min. BMI is 22 kg/m². Oral mucous membranes are dry, and the abdomen shows mild diffuse tenderness with no peritoneal signs. Laboratory results are as follows: What is the most likely cause of this patient's hyperglycemia? A)Glucocorticoid-induced diabetes mellitus B)Maturity-onset diabetes of the young C)Pancreatitis-induced diabetes mellitus D)Type 1 diabetes mellitus E)Type 2 diabetes mellitus

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Explanation: 11ec2b69_c132_e077_8f63_87479bee4e38_MD0005_00 This patient has severe hyperglycemia with anion gap metabolic acidosis and ketonemia consistent with diabetic ketoacidosis. The sudden onset of symptoms, young age, lack of obesity, and autoimmune history suggest type 1 diabetes mellitus. Type 1 diabetes is an autoimmune disorder that often occurs with other autoimmune endocrine disorders (eg, primary adrenal insufficiency, autoimmune thyroid disease). Inherited clusters of autoimmune endocrinopathies (polyglandular autoimmune syndromes [eg, Schmidt syndrome]) have been described and are likely in this patient given his family history. Nonendocrine autoimmune conditions, such as pernicious anemia, vitiligo, and celiac disease, may be associated as well. (Choice A) Glucocorticoid-induced diabetes resembles type 2 diabetes mellitus and is characterized by insulin resistance rather than absolute insulin deficiency. Ketoacidosis is uncommon. Furthermore, patients with primary adrenal insufficiency typically receive physiological doses of glucocorticoids and therefore generally do not develop glucocorticoid excess. (Choice B) Maturity-onset diabetes mellitus of the young may be misdiagnosed as type 1 diabetes due to a similar age of onset. However, patients with this condition have a positive family history (autosomal dominant single gene defect in most cases) and generally do not develop ketoacidosis but rather have modest hyperglycemia. (Choice C) Pancreatogenic diabetes is due to islet cell damage from chronic pancreatitis. Both glucagon-secreting alpha cells and beta cells are affected, which leads to an increased risk of hypoglycemia but decreased risk of ketoacidosis compared with type 1 diabetes (glucagon is required for the formation of ketone bodies). Mild elevations of serum amylase may be seen in diabetic ketoacidosis and do not indicate pancreatitis. (Choice E) Ketoacidosis is uncommon in type 2 diabetes. Caloric deprivation in acute illness in patients with type 2 diabetes may result in starvation ketosis but without a significantly increased anion gap. This patient's young age, lack of obesity, and autoimmune history make type 1 diabetes more likely than type 2. Educational objective: Type 1 diabetes is an autoimmune disorder that often occurs with other autoimmune endocrine disorders (eg, primary adrenal insufficiency, autoimmune thyroid disease). Inherited clusters of autoimmune endocrinopathies have been described. Nonendocrine autoimmune conditions, such as pernicious anemia, vitiligo, and celiac disease, may be associated as well. References: Type 1 diabetes and polyglandular autoimmune syndrome: a review. (http://www.ncbi.nlm.nih.gov/pubmed/25685279)

A 28-Year-Old Man Comes to the Emergency Department Due to a 2-Day