1. Type 1 DM
2. Type 2 DM
3. Gestational DM
4. Other Specific Types of Diabetes
a. Diabetes Resulting from Genetic Defects in Beta-Cell Function
b. Diabetes Resulting from Genetic Defects in Insulin Action
c. Diabetes Resulting from Exocrine Pancreas Diseases
d. Diabetes Secondary to Endocrine Diseases
e. Drug-induced diabetes
f. Diabetes resulting from infectious diseases
g. Forms of diabetes associated with genetic syndromes
h. Ketosis-prone diabetes
i. Malnutrition-related diabetes
Type 1 Diabetes Risk Factors
Autoimmune, genetic, and environmental factors that cause beta-cell destruction constitute the risk factors for Type 1 DM.
- Genetic predisposition: Human leukocyte antigen (HLA) genes located on the short arm of chromosome 6 (DQB1, DRB1, DR3, DR4, DR3/4), diabetogenic genes located on the major histocompatibility complex (MHC Class II), family history of Type 1 DM.
- Environmental triggers: Viral infections (Coxsackie B, EBV, Cytomegalovirus), chemical toxins, drugs (immune checkpoint inhibitors), emotional stress.
- Immune mechanism dysfunction: Loss of immune tolerance, insulitis, slow and progressive loss of pancreatic islet beta cells (mediated by TH1 CD4 and cytotoxic CD8 T lymphocytes).
- Autoantibody positivity: Anti-islet antibody, anti-insulin antibody, anti-GAD antibody, anti-IA2, anti-ZnT8.
- History of autoimmune disease: Polyglandular syndromes.
Type 2 Diabetes Risk Factors
- Risk factors for Type 2 diabetes (T2DM) are heterogeneous. Genetic, sociodemographic, clinical, and lifestyle factors that affect insulin secretion and sensitivity play a significant role in the development of T2DM.
- Genetic: Family history of diabetes (in first-degree relatives).
- Demographic Risk Factors: Age, female gender, ethnicity (Hispanic/Latino, African American, Asian American...), low socioeconomic status, low level of education.
- Lifestyle-related Risk Factors: Overweight/obesity, physical inactivity, poor dietary patterns, disrupted sleep patterns, social environment, modernization.
- Clinical Risk Factors: Impaired glucose tolerance (IGT), impaired fasting glucose (IFG), gestational diabetes (GDM), polycystic ovary syndrome (PCOS), cardiovascular disease, hypertension, hyperlipidemia, abdominal obesity, fatty liver disease, obstructive sleep apnea syndrome (OSAS), birth weight, having given birth to an infant large for gestational age (LGA) or small for gestational age (SGA).
- Medications: Glucocorticoids, antipsychotics, thiazide diuretics, HIV medications...
Note: Both types of diabetes can occur at any age. Type 2 diabetes is more common in individuals over the age of 35, whereas Type 1 diabetes is more common in individuals under the age of 35.