Diabetes mellitus is a group of metabolic disorders characterized by high blood sugar levels (hyperglycemia). The causes vary depending on the type of diabetes, but they generally involve a combination of genetic, autoimmune, lifestyle, and environmental factors.
✅ 1. Type 1 Diabetes (Autoimmune)
- Cause: Autoimmune destruction of insulin-producing beta cells in the pancreas.
- Triggers:
- Genetic predisposition (HLA genes)
- Viral infections (e.g., Coxsackievirus)
- Environmental triggers (possibly cow's milk exposure in infancy)
- Insulin deficiency is absolute.
✅ 2. Type 2 Diabetes (Lifestyle-related and Genetic)
- Cause: Insulin resistance + progressive beta-cell dysfunction.
- Major risk factors:
- Obesity (especially central)
- Sedentary lifestyle
- Unhealthy diet (high sugar/refined carbs)
- Genetics (family history)
- Age > 40 years (but increasingly seen in younger adults and children)
- Ethnicity (South Asians, Africans at higher risk)
- Metabolic syndrome
✅ 3. Gestational Diabetes (During Pregnancy)
- Cause: Hormonal changes during pregnancy leading to insulin resistance.
- Risk factors:
- Obesity
- Family history of diabetes
- History of PCOS
- Previous macrosomic baby (>4 kg)
- Age > 25 years at pregnancy
✅ 4. Secondary Diabetes (Due to other conditions)
- Pancreatic disorders:
- Chronic pancreatitis
- Pancreatic cancer
- Cystic fibrosis
- Hemochromatosis
- Endocrine disorders:
- Cushing's syndrome
- Acromegaly
- Pheochromocytoma
- Hyperthyroidism
- Drugs:
- Glucocorticoids
- Thiazide diuretics
- Atypical antipsychotics (e.g., olanzapine)
- Statins (in rare cases)
- Infections:
- Congenital rubella
- CMV
✅ 5. Genetic Defects (Monogenic Diabetes)
- MODY (Maturity Onset Diabetes of the Young): Due to single gene mutations affecting insulin production.
- Neonatal Diabetes: Appears in the first 6 months of life.
Summary Table:
Type | Main Cause | Key Features |
---|---|---|
Type 1 | Autoimmune beta-cell destruction | Insulin-dependent, early onset |
Type 2 | Insulin resistance + beta-cell dysfunction | Lifestyle-related, gradual onset |
Gestational | Pregnancy-related insulin resistance | Temporary, risk of future T2DM |
Secondary | Other diseases/drugs affecting glucose | Treat underlying condition |
Genetic (MODY, NDM) | Single gene mutations | Rare, diagnosed early or in families |
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