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.