Table 1.

Etiologic classification of diabetes mellitus

Type 1 diabetes (β-cell destruction, usually leading to absolute insulin deficiency) Immune mediated Idiopathic Type 2 diabetes (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance) Other specific types Genetic defects of β-cell function Chromosome 12, HNF-1α (MODY3) Chromosome 7, glucokinase (MODY2) Chromosome 20, HNF-4α (MODY1) Chromosome 13, insulin promoter factor-1 (IPF-1; MODY4) Chromosome 17, HNF-1β (MODY5) Chromosome 2, NeuroD1 (MODY6) Mitochondrial DNA Others Genetic defects in insulin action Type A insulin resistance Leprechaunism Rabson-Mendenhall syndrome Lipoatrophic diabetes Others Diseases of the exocrine pancreas Pancreatitis Trauma/pancreatectomy Neoplasia Cystic fibrosis Hemochromatosis Fibrocalculous pancreatopathy Others Endocrinopathies Acromegaly Cushing's syndrome Glucagonoma Pheochromocytoma Hyperthyroidism Somatostatinoma Aldosteronoma Others Drug or chemical induced Vacor Pentamidine Nicotinic acid Glucocorticoids Thyroid hormone Diazoxide β-adrenergic agonists Thiazides Dilantin γ-Interferon Others Infections Congenital rubella Cytomegalovirus Others Uncommon forms of immune-mediated diabetes “Stiff-man” syndrome Anti-insulin receptor antibodies Others Other genetic syndromes sometimes associated with diabetes Down syndrome Klinefelter syndrome Turner syndrome Wolfram syndrome Friedreich ataxia Huntington chorea Laurence-Moon-Biedl syndrome Myotonic dystrophy Porphyria Prader-Willi syndrome Others Gestational diabetes mellitus

Patients with any form of diabetes may require insulin treatment at some stage of their disease. Such use of insulin does not, of itself, classify the patient.