INSULIN

Introduction:

• Insulin is a peptide hormone produced by beta cells in the pancreas.

• It regulates blood glucose levels by facilitating glucose uptake into cells (liver, fat, and muscle tissues) and aids in the metabolism of carbohydrates, fats, and proteins.

• In diabetes, impaired insulin production or function necessitates external administration.

Types of Insulin

1. Rapid-Acting (Onset: ~15 min, Peak: 1-2 hrs, Duration: 3-5 hrs)

   • Examples: Lispro, Aspart, Glulisine

   • Uses: Mealtime glucose control.

2. Short-Acting (Onset: ~30 min, Peak: 2-3 hrs, Duration: 5-8 hrs)

   • Examples: Regular Insulin (Humulin R, Novolin R)

   • Uses: Pre-meal and basal needs.

3. Intermediate-Acting (Onset: ~2-4 hrs, Peak: 4-12 hrs, Duration: 12-18 hrs)

   • Examples: NPH Insulin (Humulin N, Novolin N)

   • Uses: Basal coverage.

4. Long-Acting (Onset: ~1-2 hrs, Peak: Minimal, Duration: ~24 hrs)

   • Examples: Glargine, Detemir, Degludec

   • Uses: Basal insulin, once/twice daily.

5. Ultra-Long-Acting (Onset: ~30-90 min, Peak: None, Duration: >24 hrs)

   • Examples: Degludec

   • Uses: Extended basal needs.

Mechanism of Action

Insulin lowers blood glucose by:

• Facilitating Glucose Uptake: Promotes entry of glucose into muscle and fat cells.

• Inhibiting Gluconeogenesis: Reduces glucose production in the liver.

• Promoting Glycogen Synthesis: Enhances storage of glucose as glycogen in the liver and muscles.

• Stimulating Lipogenesis: Encourages fat storage and inhibits lipolysis.

Uses

• Type I Diabetes Mellitus: Essential for survival due to absolute insulin deficiency.

• Type II Diabetes Mellitus: Used when oral antidiabetics are insufficient to control blood glucose levels.

• Gestational Diabetes: Manages elevated blood sugar levels during pregnancy.

• Hyperkalemia: Insulin shifts potassium into cells, lowering blood potassium levels.

Side Effects

• Hypoglycemia: Low blood sugar levels, presenting as dizziness, sweating, confusion, and in severe cases, loss of consciousness.

• Weight Gain: Increased fat storage due to insulin’s anabolic effects.

• Injection Site Reactions: Redness, swelling, or itching at the injection site.

• Allergic Reactions: Rare but may include rash or anaphylaxis.

• Lipodystrophy: Changes in fat tissue at injection sites from repeated use.