RT Book, Section A1 Jameson, J. Larry A1 Fauci, Anthony S. A1 Kasper, Dennis L. A1 Hauser, Stephen L. A1 Longo, Dan L. A1 Loscalzo, Joseph SR Print(0) ID 1167068671 T1 Diabetes Mellitus T2 Harrison's Manual of Medicine, 20e YR 2020 FD 2020 PB McGraw-Hill Education PP New York, NY SN 9781260455342 LK accessmedicine.mhmedical.com/content.aspx?aid=1167068671 RD 2024/03/28 AB Diabetes mellitus (DM) comprises a group of metabolic disorders that share the common feature of hyperglycemia. DM is currently classified on the basis of the pathogenic process that leads to hyperglycemia. Type 1 DM is characterized by insulin deficiency and a tendency to develop ketosis—it is most commonly caused by autoimmune destruction of the pancreatic islet beta cells. Type 2 DM is a heterogeneous group of disorders characterized by variable degrees of insulin resistance, impaired insulin secretion, and excessive hepatic glucose production—it is strongly associated with obesity. Other specific types include DM caused by genetic defects (maturity-onset diabetes of the young [MODY] and other rare monogenic disorders), diseases of the exocrine pancreas (chronic pancreatitis, cystic fibrosis, hemochromatosis), endocrinopathies (acromegaly, Cushing’s syndrome, glucagonoma, pheochromocytoma, hyperthyroidism), drugs (nicotinic acid, glucocorticoids, thiazides, protease inhibitors), and pregnancy (gestational DM). The phenotype of these monogenetic and secondary types of DM typically resembles type 2 DM; its severity depends on the degree of beta cell dysfunction and prevailing insulin resistance.