What are the types of diabetes mellitus (DM) and their subtypes?

From the Guidelines

The main types of diabetes mellitus (DM) are Type 1, Type 2, and Gestational diabetes, with several subtypes within each category, as classified by the American Diabetes Association in 2023 1. The classification of diabetes is crucial for determining therapy and can be divided into four main categories:

• Type 1 diabetes (due to autoimmune b-cell destruction, usually leading to absolute insulin deficiency, including latent autoimmune diabetes of adulthood)
• Type 2 diabetes (due to a non-autoimmune progressive loss of adequate b-cell insulin secretion frequently on the background of insulin resistance and metabolic syndrome)
• Specific types of diabetes due to other causes, e.g., monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young), diseases of the exocrine pancreas (such as cystic fibrosis and pancreatitis), and drug- or chemical-induced diabetes (such as with glucocorticoid use, in the treatment of HIV/AIDS, or after organ transplantation)
• Gestational diabetes mellitus (diabetes diagnosed in the second or third trimester of pregnancy that was not clearly overt diabetes prior to gestation) 1. Type 1 diabetes and type 2 diabetes are heterogeneous diseases in which clinical presentation and disease progression may vary considerably, and some individuals cannot be clearly classified as having type 1 or type 2 diabetes at the time of diagnosis 1. Understanding these types is crucial for proper diagnosis and treatment, as each type has distinct causes and may require different management strategies to effectively control blood sugar levels and prevent complications, ultimately improving morbidity, mortality, and quality of life 1.

From the Research

Types of Diabetes Mellitus

• Type 1 diabetes mellitus (insulin-dependent) 2
• Type 2 diabetes mellitus (non-insulin-dependent) 2, 3, 4
• Gestational diabetes mellitus 2, 3

Subtypes of Diabetes Mellitus

• Maturity-onset diabetes of the young (MODY) 5
  • HNF1A 5
  • GCK 5
  • HNF4A 5
• Neonatal diabetes mellitus 5
  • Permanent neonatal diabetes mellitus (PNDM) 5
  • Transient neonatal diabetes mellitus (TNDM) 5
• Latent Autoimmune Diabetes in Adults (LADA) 4, 6

Other Forms of Diabetes

• Monogenic forms of diabetes mellitus 5
• Autoimmune diabetes 4, 6