A 45-year-old woman comes to the physician because of frequent urination and increasing fatigue over the last 2 weeks. She urinates large volumes and gets up twice each night to urinate. She also thinks that she may have lost some weight during this time. Her general health has been good with the exception of discoid lupus erythematosus, which causes her to experience occasional skin rashes and photosensitivity.
Her blood pressure is 130/78 mm Hg and pulse is 75/min. Her BMI is 21 kg/m². Her mucous membranes appear moist. Physical examination is unremarkable except for scattered areas of skin depigmentation.
Fasting laboratory studies reveal:

Which of the following is most likely to establish the cause of this patient's current condition?

Question

A 45-year-old woman comes to the physician because of frequent urination and increasing fatigue over the last 2 weeks. She urinates large volumes and gets up twice each night to urinate. She also thinks that she may have lost some weight during this time. Her general health has been good with the exception of discoid lupus erythematosus, which causes her to experience occasional skin rashes and photosensitivity.
Her blood pressure is 130/78 mm Hg and pulse is 75/min. Her BMI is 21 kg/m². Her mucous membranes appear moist. Physical examination is unremarkable except for scattered areas of skin depigmentation.
Fasting laboratory studies reveal:

Which of the following is most likely to establish the cause of this patient's current condition?

Quizplus · Accepted Answer

This patient's presentation is consistent with latent autoimmune diabetes of adulthood (LADA), which is seen in nearly 10% of adults with presumed type 2 diabetes who actually have type 1 diabetes. Patients with LADA have circulating anti-islet cell antibodies (ICA) and antibodies to glutamic acid decarboxylase (GAD). Patients with these antibodies usually have a lower BMI, are at increased risk of ketoacidosis, respond poorly to dietary therapy and oral diabetic medications, and require insulin much sooner. A clinical screening tool for LADA has been developed (shown below). 11ec193a_97ad_a5b9_853d_1bd8029c7c8e_MD0002_00 (Choice A) Abdominal imaging with CT scan can identify pancreatic tumors (e.g., somatostatinoma) or chronic pancreatitis that can affect glucose metabolism. Somatostatinomas usually present with diabetes, gallstones, and diarrhea with steatorrhea. Chronic pancreatitis can lead to early glucose intolerance with overt diabetes later in the disease course. However, this patient's lack of chronic abdominal pain or diarrhea makes these diagnoses less likely. (Choice C) Anti-insulin receptor antibodies can potentially block insulin and cause diabetes, but it is a less common cause than LADA. (Choice D) Anti-tissue transglutaminase antibodies are seen in celiac sprue, which usually causes iron-deficiency anemia. This patient's normal hematocrit makes this scenario unlikely. (Choice E) Hyperthyroidism can interfere with glucose metabolism and cause impaired glucose tolerance, but it usually does not cause overt diabetes. Educational objective: Latent autoimmune diabetes of adulthood (LADA) is type 1 diabetes mellitus that manifests later in life, usually in thin patients age >35 but < 50 with abrupt symptom onset, and a family/personal history of autoimmune disease. These patients have anti-islet cell and glutamic acid decarboxylase antibodies, are at increased risk of ketoacidosis, respond poorly to dietary therapy and oral diabetic medications, and usually require insulin earlier. __________ References: A clinical screening tool to identify autoimmune diabetes in adulthood. (http://www.ncbi.nlm.nih.gov/pubmed/16644622) Latent auto-immune diabetes mellitus in adults (LADA): the role of antibodies to glutamic acid decarboxylase in diagnosis and prediction of insulin dependency. (http://www.ncbi.nlm.nih.gov/pubmed/8033530)

A 45-Year-Old Woman Comes to the Physician Because of Frequent