What are the different types of insulin, including brand names such as Lantus (glargine) and Humalog (lispro), and how are their doses initiated?

Insulin Types, Brand Names, and Dosing Guidelines

Start basal insulin at 10 units daily or 0.1-0.2 units/kg for most patients with type 2 diabetes, titrating by 2-4 units (or 10-15%) once or twice weekly until fasting glucose targets are met, then add rapid-acting prandial insulin at 4 units per meal if A1C remains above target. 1

Insulin Categories and Brand Names

Basal (Long-Acting) Insulins

• Insulin glargine: Lantus (U-100), Toujeo (U-300), Basaglar 1, 2

  • Onset: ~1 hour, peakless profile, duration up to 24 hours 2
  • Administered once daily at consistent time 2

• Insulin detemir: Levemir 1

  • May require twice-daily dosing for 24-hour coverage 2

• Insulin degludec: Tresiba (U-100, U-200) 1

  • Ultra-long duration, available in concentrated formulation 1

• NPH (Neutral Protamine Hagedorn): Humulin N, Novolin N 1

  • Intermediate-acting, more affordable but higher hypoglycemia risk 1
  • Can be dosed once or twice daily 1

Rapid-Acting (Prandial) Insulins

• Insulin lispro: Humalog (U-100, U-200) 1, 3
• Insulin aspart: Novolog, Fiasp 1, 3
• Insulin glulisine: Apidra 1
  • All administered immediately before meals 1
  • Preferred over regular insulin due to faster onset 1

Premixed Insulins

• 70/30 formulations: Novolog 70/30, Humalog Mix 75/25, Humulin 70/30 1, 4
  • Fixed ratios of basal and prandial components 1
  • Administered twice daily, 30 minutes before breakfast and dinner 4
  • Require fixed meal schedules 5

Concentrated Formulations

• U-500 regular insulin: For patients requiring >200 units/day 1, 2
• U-300 glargine (Toujeo): Requires 10-18% higher doses than U-100 glargine 2
• U-200 lispro and degludec: Reduce injection volume for high-dose patients 1

When to Use Each Insulin Type

Type 2 Diabetes Progression

Initial Insulin Therapy:

• Start basal insulin when oral agents fail to achieve A1C targets 1
• Continue metformin; consider one additional non-insulin agent 1
• Basal insulin alone is the most convenient initial regimen 1

Intensification Criteria:

• If basal insulin dose exceeds 0.5 units/kg/day and A1C remains above target, advance to combination therapy 1, 2
• If fasting glucose is controlled but A1C elevated, add prandial coverage 1
• Consider GLP-1 receptor agonist before or with prandial insulin for weight and hypoglycemia benefits 1, 4

Severe Hyperglycemia:

• Start insulin immediately when glucose ≥300-350 mg/dL and/or A1C ≥10-12%, especially with symptoms or weight loss 1
• Use basal plus mealtime insulin as preferred initial regimen in this scenario 1

Type 1 Diabetes

• Always requires basal-bolus therapy from diagnosis 2, 6
• Basal insulin comprises 40-60% of total daily dose 1, 2
• Rapid-acting analogs preferred for prandial coverage 1, 6

Starting Dose Algorithms

Basal Insulin Initiation

Standard Starting Dose:

• 10 units daily OR 0.1-0.2 units/kg body weight 1
• Administer at consistent time each day (typically bedtime for glargine) 2

Titration Protocol:

• Increase by 2-4 units (or 10-15%) once or twice weekly until fasting glucose target achieved 1
• Set specific fasting plasma glucose target (typically 80-130 mg/dL) 1
• For hypoglycemia without clear cause, decrease dose by 10-20% 1

Type 2 Diabetes Typical Requirements:

• Generally require ≥1 unit/kg/day due to insulin resistance 2
• Higher than type 1 diabetes requirements 1, 2

Adding Prandial Insulin

When to Add:

• Basal insulin optimally titrated to acceptable fasting glucose but A1C remains above target 1
• Basal dose >0.5 units/kg/day with inadequate control 1, 2

Starting Dose Options:

1. 4 units per meal 1
2. 0.1 units/kg per meal 1
3. 10% of basal dose per meal (if A1C <8%) 1

Stepwise Approach (Basal-Plus Strategy):

• Start with one injection before the largest meal or meal with greatest postprandial excursion 1, 5
• Add second injection if needed, then third 1, 5
• Consider decreasing basal insulin by 4 units or 10% when adding prandial insulin 1

Prandial Titration:

• Increase by 1-2 units or 10-15% twice weekly based on pre-meal and 2-hour postprandial glucose 1
• For hypoglycemia, decrease corresponding dose by 10-20% 1

Alternative: Premixed Insulin

Starting Dose:

• 10 units or 0.1-0.2 units/kg/day divided into two equal doses 4
• Administer 30 minutes before breakfast and dinner 4
• Less flexible but simpler than basal-bolus 1, 5

Twice-Daily NPH Conversion

When Converting from Bedtime NPH:

• Total dose = 80% of current bedtime NPH dose 1
• Give 2/3 before breakfast, 1/3 at bedtime 1
• Adjust based on fasting and pre-dinner glucose patterns 1

Critical Dosing Considerations

Overbasalization Warning

• Do not continue escalating basal insulin beyond 0.5 units/kg/day if A1C remains elevated 1, 2
• Clinical signals: elevated bedtime-to-morning glucose differential, hypoglycemia, high variability 1
• Add prandial coverage or GLP-1 receptor agonist instead 1, 2

Concentrated Insulin Caveats

• U-300 glargine requires 10-18% higher total daily dose than U-100 formulations 2
• U-500 regular insulin has both prandial and basal properties; use only when total daily dose >200 units 1, 2
• Use dedicated syringes or pens to prevent dosing errors 1

Combination Therapy Adjustments

• Continue metformin when adding insulin 1
• Discontinue sulfonylureas, DPP-4 inhibitors when using basal-bolus or premixed regimens 1
• Consider SGLT2 inhibitors or pioglitazone to reduce insulin requirements in high-dose patients 1
• GLP-1 receptor agonists provide complementary benefits: less weight gain and hypoglycemia than insulin intensification alone 1, 4

Special Populations

• Insulin resistance (type 2 diabetes): Typically require ≥1 unit/kg/day 1, 2
• Puberty, pregnancy, illness: May require higher doses 2
• Elderly or hypoglycemia-prone: Start conservatively, titrate slowly 1

Monitoring Requirements

• Self-monitoring of blood glucose essential for dose titration 1
• Fasting glucose guides basal insulin adjustments 1
• Pre-meal and 2-hour postprandial glucose guide prandial insulin adjustments 1, 4
• Evaluate A1C every 2-3 months 4

Common Pitfalls to Avoid

• Never mix or dilute insulin glargine with other insulins due to low pH 2
• Failing to adjust prandial insulin when holding or reducing basal insulin leads to inadequate control 2
• Overlapping insulin action between premixed formulations and basal insulin may cause hypoglycemia 4
• Delaying insulin initiation or intensification worsens long-term outcomes 1