How do I prescribe Lantus (insulin glargine) with bolus insulin (e.g., Novolog [insulin aspart] or Humalog [insulin lispro])?

Prescribing Lantus (Insulin Glargine) with Bolus Insulin

Start Lantus at 10 units once daily (or 0.1-0.2 units/kg/day) at any consistent time of day, combined with 4 units of rapid-acting insulin (Novolog/Humalog) before each meal, or start with a single mealtime dose before the largest meal. 1, 2

Initial Basal Insulin (Lantus) Setup

• Dose: Begin with 10 units once daily or 0.1-0.2 units/kg body weight 1
• Timing: Administer at any time of day (breakfast, dinner, or bedtime), but maintain the same time daily for consistency 3
• Morning administration reduces nocturnal hypoglycemia risk (59.5% incidence) compared to dinner (71.9%) or bedtime (77.5%) dosing 3

Basal Titration Protocol

• Increase by 2 units every 3 days until fasting plasma glucose reaches target (typically 80-130 mg/dL) without hypoglycemia 1
• If hypoglycemia occurs without clear cause, reduce dose by 10-20% 1
• Maximum effective basal dose is approximately 0.5 units/kg/day; doses exceeding this suggest need for prandial insulin intensification 1

Adding Bolus Insulin (Novolog/Humalog)

When to Add Prandial Insulin

• Add when basal insulin is optimized (fasting glucose at target) but HbA1c remains above goal 2
• Add when basal dose exceeds 0.5 units/kg/day without achieving glycemic targets 2

Initial Bolus Dosing Strategy

Start with ONE of these approaches:

1. Single meal approach (recommended to start): 4 units before the largest meal or meal with highest postprandial glucose 1, 2
2. Three-meal approach: 4 units before each meal 2
3. Weight-based: 0.1 units/kg per meal 2
4. Basal-based: 10% of basal dose per meal 1, 2

• When starting prandial insulin, consider reducing basal dose by 4 units or 10% to prevent hypoglycemia 1, 2

Bolus Titration

• Increase each mealtime dose by 1-2 units or 10-15% twice weekly based on postprandial glucose readings 1
• If hypoglycemia occurs, reduce corresponding dose by 10-20% 1

Critical Timing Requirements

• Novolog/Humalog: Inject 0-5 minutes before meals (within 5-10 minutes per FDA label) 2, 4
• Lantus: Once daily at consistent time; can be given at any time but morning dosing may reduce nocturnal hypoglycemia 3

Medication Adjustments

• Continue metformin in most cases 2
• Discontinue sulfonylureas to reduce hypoglycemia risk 2
• Discontinue DPP-4 inhibitors as they become redundant with prandial insulin 2

Administration Details

Lantus-Specific Rules

• Never mix Lantus with any other insulin due to its acidic pH (pH 4.0) 1, 5, 6
• Administer as separate injection from bolus insulin 5
• Inject subcutaneously in abdomen, thigh, buttocks, or upper arm 4
• Rotate injection sites within same region to prevent lipodystrophy 4

Bolus Insulin Administration

• Inject subcutaneously in abdomen (fastest absorption), thigh, buttocks, or upper arm 4
• Rotate sites within same region 4
• Appears clear and colorless; do not use if cloudy or discolored 4

Common Pitfalls to Avoid

1. Do not delay adding prandial insulin when basal alone is insufficient—this causes prolonged hyperglycemia 2
2. Do not mix Lantus with rapid-acting insulin in the same syringe 1, 5
3. Do not forget to reduce basal dose when initiating prandial insulin to prevent hypoglycemia 2
4. Ensure carbohydrate counting education before starting mealtime insulin 2
5. Do not use Lantus in insulin pumps—it is designed for subcutaneous injection only 4

Monitoring and Follow-up

• Check fasting glucose to titrate basal insulin 1
• Check pre-meal and 2-hour postprandial glucose to titrate bolus insulin 1
• Reassess every 2 weeks during titration phase 7
• Target HbA1c ≤7.0% for most patients 1, 8