What are the different types of insulin and their uses?

Types of Insulin and Their Uses

Insulin is available in rapid-, short-, intermediate-, and long-acting types that can be injected separately or mixed in the same syringe to provide optimal glycemic control for patients with diabetes. 1

Classification of Insulin Types

Rapid-Acting Insulin

• Examples: Insulin lispro, insulin aspart, insulin glulisine
• Onset: 5-15 minutes
• Peak: 1-2 hours
• Duration: 3-5 hours
• Uses: Mealtime coverage, correction of high blood glucose
• Appearance: Clear solution 2
• Administration: Immediately before meals or within 15 minutes before a meal when mixed with intermediate-acting insulin 1

Short-Acting Insulin

• Examples: Regular human insulin
• Onset: 30 minutes
• Peak: 2-3 hours
• Duration: 5-8 hours
• Uses: Mealtime coverage, correction of high blood glucose, intravenous administration
• Appearance: Clear solution 1
• Administration: 30 minutes before meals 1

Intermediate-Acting Insulin

• Examples: NPH (Neutral Protamine Hagedorn)
• Onset: 1-2 hours
• Peak: 6-8 hours
• Duration: 12-18 hours
• Uses: Basal insulin coverage
• Appearance: Cloudy suspension 1
• Administration: Once or twice daily 1

Long-Acting Insulin

• Examples: Insulin glargine, insulin detemir, insulin degludec
• Onset: 1-2 hours
• Peak: Minimal or no peak
• Duration: 20-42+ hours
• Uses: Basal insulin coverage
• Appearance: Clear solution (glargine) 1
• Administration: Once daily (sometimes twice for detemir) 2

Clinical Applications

Basal Insulin Therapy

• Long-acting analogs (glargine, detemir, degludec) provide more consistent coverage with less hypoglycemia risk compared to NPH insulin 1
• Starting doses typically range from 0.1-0.2 units/kg/day 2
• Total daily insulin requirements typically range from 0.4-1.0 units/kg/day, with approximately 50% as basal insulin 2

Prandial Insulin Therapy

• Rapid-acting analogs provide better postprandial glucose control than regular human insulin 3
• Options for intensification beyond basal insulin include:
  1. Adding a single injection of rapid-acting insulin before the largest meal
  2. Adding a GLP-1 receptor agonist
  3. Switching to twice-daily premixed insulin 1

Premixed Insulin Formulations

• Contain fixed proportions of intermediate-acting and short/rapid-acting insulin
• Examples: 70% NPH/30% regular, 50% NPH/50% regular, 75% NPL/25% insulin lispro 1
• Advantages: Fewer injections, simplified regimen
• Disadvantages: Less flexibility, requires relatively fixed meal schedule and carbohydrate content 1

Special Insulin Formulations

Concentrated Insulins

• U-500 regular insulin: 5 times as concentrated as U-100, has both prandial and basal properties
• U-300 glargine and U-200 degludec: Allow higher doses per volume
• U-200 lispro: Reduces injection volume for large doses 1
• Indicated for patients requiring large insulin doses (>200 units/day for U-500) 1

Inhaled Insulin

• Available for prandial use with limited dosing range
• Contraindicated in patients with chronic lung disease
• Not recommended for smokers 1

Insulin Mixing Guidelines

1. Rapid-acting insulin can be mixed with NPH, lente, and ultralente 1
2. Currently available NPH and short-acting insulin formulations when mixed may be used immediately or stored for future use 1
3. Insulin glargine should not be mixed with other forms of insulin due to its acidic pH 1
4. Phosphate-buffered insulins (e.g., NPH) should not be mixed with lente insulins 1
5. When rapid-acting insulin is mixed with intermediate or long-acting insulin, inject within 15 minutes before a meal 1

Clinical Considerations

Advantages of Insulin Analogs

• Rapid-acting analogs provide better postprandial glucose control with less risk of late hypoglycemia compared to regular human insulin 4
• Long-acting analogs provide more consistent basal coverage with less risk of nocturnal hypoglycemia compared to NPH insulin 5
• Treatment satisfaction is often higher with analog insulins compared to human insulins 3

Common Pitfalls and Caveats

1. Incorrect mixing: Mixing certain insulins (e.g., glargine with others) can alter their pharmacokinetics and effectiveness 1
2. Inappropriate storage: Extreme temperatures (<36°F or >86°F) can reduce potency 1
3. Inadequate dose adjustment: Failure to titrate insulin doses based on blood glucose patterns 2
4. Switching insulin types without supervision: Changes in insulin types should always be done under medical supervision 1
5. Mismatched timing: Using rapid-acting insulin too far in advance of meals or regular insulin too close to meals 1

By selecting the appropriate insulin type and regimen based on individual patient needs and glucose patterns, optimal glycemic control can be achieved while minimizing the risk of hypoglycemia.