1. DM type 1: destruction of β cells, usually leading to absolute deficiency of insulin.

2. DM type 2: caused by progressive reduction of insulin secretion due to insulin resistance.

3. Gestational diabetes: diabetes diagnosed in the second or third gestational quarter that was clearly not present before.

4. Specific types of diabetes due to other causes: monogenic syndromes of diabetes (neonatal diabetes and MODY), diseases of the exocrine pancreas (such as cystic fibrosis), and drugs/chemically induced (such as the use of glucocorticoids, treatment for HIV/AIDS or after organ transplant).