T2DM

Diabetes – Meaning & Pathophysiology (Type 2)

Definition:
Diabetes mellitus is a metabolic disorder characterized by elevated blood glucose levels (hyperglycemia) due to problems with insulin production, secretion, or action.

Normal Physiology of Insulin

• Pancreas (behind stomach) produces insulin from beta cells.

• Trigger: High blood glucose (e.g., after meals).

• Target Organs:

  • Muscle cells: ↑ glucose uptake (via transporters).

  • Adipose tissue: Stores glucose as fat.

  • Liver: Promotes glycogenesis (glucose → glycogen), glycolysis, and fat storage.

• Purpose: Decrease blood glucose and store energy.

Pathophysiology of Type 2 Diabetes

• Core Problem: Insulin resistance → insulin receptors in liver, adipose tissue, and skeletal muscle do not respond effectively.

• Consequences:

  • Persistent hyperglycemia.

  • Pancreas compensates by secreting more insulin (hyperinsulinemia).

  • Over time, beta-cell dysfunction and atrophy → insulin deficiency.

Clinical Manifestations

1. Polyuria – frequent urination (due to glucose spilling into urine → osmotic diuresis).

2. Polydipsia – excessive thirst (compensating for fluid loss).

3. Polyphagia – excessive hunger (cells starved of glucose despite high blood sugar).

4. Glycosuria – glucose in urine.

5. Dehydration – from fluid loss, may cause hyperosmolar state.

6. Complications: Prolonged dehydration → renal failure; chronic hyperglycemia damages blood vessels, nerves, and organs.

Causes & Risk Factors

• Genetic predisposition.

• Poor diet and sedentary lifestyle.

• Obesity (especially central/visceral).

Disease Progression

• Early: Insulin resistance → pancreas overworks.

• Later: Beta-cell exhaustion → ↓ insulin secretion.

• Advanced: Insulin injections often required.