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. Chromosome 13, insulin promoter factor-1 (IPF-1; MODY4)
        5. Chromosome 17, HNF-1β (MODY5)
        6. Chromosome 2, NeuroD1 (MODY6)
        7. Mitochondrial DNA
        8. 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.