In 1979, National diabetes data group of USA categorized diabetics into seven groups.

1. Type I, Insulin Dependent Diabetes (IDDM), is characterized by a deficiency of insulin, and injected insulin deficiency is believed to be caused by damage to the islet cells of the pancreas either by viral infection or by an auto immune process.
2. Type II, non-insulin dependent diabetes (IDDM), insulin is lacking in effectiveness rather than deficient. This type is often associated with obesity. Insulin is relatively ineffective for controlling hyperglycemia but may be required for the prevention of ketosis.
3. Diabetes secondary to other conditions pancreatic diseases such as carcinoma, chronic pancreatitis and hemochromatosis
   • cushing's syndrome
   • - Drugs, such as corticosteroids, estrogens, thiazide diuretics, tricycles anti depressants, phenytoin, lithium, indomethacin, propranolol genetic syndromes, congenital lipodystrophy.
4. Impaired glucose tolerance (IGT), formerly chemical or GTP diabetes, is impaired glucose tolerance without clinical diabetes. Some of these if followed, go on to develop clinical diabetes, the risk depending on the level of blood glucose.
5. Gestational diabetes (GDM) is diabetes first developing during pregnancy, which remits after the pregnancy.
6. Previous abnormalities of glucose tolerance (prev. AGT) formerly latent diabetes refers to people whose glucose tolerance has reverted from high to normal levels.
7. Potential abnormality of glucose tolerance (pot. AGT) refers to people who are at risk for diabetes by reason of family history or race.