What types of insulin are available for a patient with diabetes requiring insulin therapy?

Available Insulin Types for Diabetes Management

Insulin formulations are categorized into basal, prandial (mealtime), and premixed preparations, with both human insulins and analog insulins available across these categories. 1

Basal (Long-Acting) Insulins

Basal insulins provide background glucose control over 12-24+ hours:

• Intermediate-acting: Neutral Protamine Hagedorn (NPH) insulin, which has a duration of action with a pronounced peak and may be a more affordable option despite higher hypoglycemia risk 1
• Long-acting analogs (U-100 formulations): Insulin glargine, insulin detemir, and insulin degludec, which have flatter, more constant activity profiles with less hypoglycemia and weight gain compared to NPH 1, 2
• Ultra-long-acting concentrated formulations: U-300 glargine and U-200 degludec, which have longer durations of action than their U-100 counterparts and allow higher doses per volume 1

Prandial (Mealtime) Insulins

Prandial insulins cover glucose excursions from meals:

• Short-acting human insulin: Regular insulin (also called Actrapid), with onset in 30 minutes, peak at 2-3 hours, and duration of 6-8 hours 3, 2
• Rapid-acting analogs: Insulin lispro, insulin aspart, and insulin glulisine, which have quicker onset and peak with shorter duration than regular insulin, resulting in better postprandial control and less hypoglycemia 1
• Ultra-rapid formulations: Faster-acting insulin aspart and faster-acting insulin lispro, which have enhanced absorption profiles providing additional postprandial glucose reduction 1, 3
• Inhaled insulin: Available for prandial use with rapid peak and shortened duration, but contraindicated in chronic lung disease (asthma, COPD) and requires spirometry monitoring 1

Premixed Insulin Combinations

Premixed insulins contain fixed ratios of basal and prandial components for simplified dosing:

• Human insulin mixtures: 70/30 NPH/regular insulin mix 1
• Analog mixtures: 70/30 aspart mix, 75/25 lispro mix, 50/50 lispro mix, and 70/30 degludec/aspart mix 1

The main disadvantage is requiring relatively fixed meal schedules and carbohydrate content per meal. 1

Concentrated Insulin Formulations

For patients requiring high insulin doses (>200 units/day):

• U-500 regular insulin: Five times more concentrated than U-100, with delayed onset and longer duration having both prandial and basal properties, available in prefilled pens and vials with dedicated syringes 1
• U-200 insulin lispro: Concentrated rapid-acting formulation reducing injection volume, available only in prefilled pens to minimize dosing errors 1

Fixed-Ratio Combination Products

Once-daily combinations of basal insulin plus GLP-1 receptor agonist:

• Insulin glargine plus lixisenatide 1
• Insulin degludec plus liraglutide 1

Critical Selection Considerations

When choosing insulin type, prioritize these factors:

• Hypoglycemia risk: Analog insulins (both rapid-acting and long-acting) cause less hypoglycemia than human insulins (regular and NPH), particularly nocturnal hypoglycemia 1, 2, 4
• Cost considerations: NPH and regular insulin are more affordable alternatives when analog insulins are prohibitively expensive, though their pharmacodynamic profiles are suboptimal 1
• Dosing flexibility: Rapid-acting analogs offer greater meal planning flexibility than premixed insulins or regular insulin 1, 3
• Injection frequency tolerance: Premixed insulins reduce injection burden but sacrifice flexibility 1

Common Pitfalls to Avoid

Critical errors in insulin selection and use:

• Do not substitute long-acting or intermediate-acting insulins for prandial insulins—only short-acting or rapid-acting insulins are appropriate mealtime replacements 3
• Concentrated insulins require dedicated delivery devices (prefilled pens or dedicated syringes) to prevent potentially fatal dosing errors 1
• Any insulin substitution requires medical supervision with informed consent and increased glucose monitoring during transition 3
• Regular insulin has 6-8 hour duration creating increased postprandial and nocturnal hypoglycemia risk compared to rapid-acting analogs 3, 2