Table 1—

Etiologic classification of diabetes mellitus

I. Type 1 diabetes* (β-cell destruction, usually leading to absolute insulin deficiency)
 A. Immune mediated
 B. Idiopathic
II. Type 2 diabetes* (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance)
III. Other specific types
 A. Genetic defects of β-cell function
  1. Chromosome 12, HNF-1α (MODY3)
  2. Chromosome 7, glucokinase (MODY2)
  3. Chromosome 20, HNF-4α (MODY1)
  4. Mitochondrial DNA
  5. Others
 B. Genetic defects in insulin action
  1. Type A insulin resistance
  2. Leprechaunism
  3. Rabson-Mendenhall syndrome
  4. Lipoatrophic diabetes
  5. Others
 C. Diseases of the exocrine pancreas
  1. Pancreatitis
  2. Trauma/pancreatectomy
  3. Neoplasia
  4. Cystic fibrosis
  5. Hemochromatosis
  6. Fibrocalculous pancreatopathy
  7. Others
 D. Endocrinopathies
  1. Acromegaly
  2. Cushing’s syndrome
  3. Glucagonoma
  4. Pheochromocytoma
  5. Hyperthyroidism
  6. Somatostatinoma
  7. Aldosteronoma
  8. Others
 E. Drug- or chemical-induced
  1. Vacor
  2. Pentamidine
  3. Nicotinic acid
  4. Glucocorticoids
  5. Thyroid hormone
  6. Diazoxide
  7. β-adrenergic agonists
  8. Thiazides
  9. Dilantin
  10. α-Interferon
  11. Others
 F. Infections
  1. Congenital rubella
  2. Cytomegalovirus
  3. Others
 G. Uncommon forms of immune-mediated diabetes
  1. “Stiff-man” syndrome
  2. Anti-insulin receptor antibodies
  3. Others
 H. Other genetic syndromes sometimes associated with diabetes
  1. Down’s syndrome
  2. Klinefelter’s syndrome
  3. Turner’s syndrome
  4. Wolfram’s syndrome
  5. Friedreich’s ataxia
  6. Huntington’s chorea
  7. Laurence-Moon-Biedl syndrome
  8. Myotonic dystrophy
  9. Porphyria
  10. Prader-Willi syndrome
  11. Others
IV. Gestational diabetes mellitus (GDM)
  • *

    * 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.