Tuesday, June 3, 2025

Causes of Diabetes

 

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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