When should Humalog (insulin lispro) be added to Lantus (insulin glargine) for a patient with uncontrolled postprandial glucose levels?

When to Add Humalog to Lantus

Add Humalog (prandial insulin) to Lantus when fasting glucose is at target but HbA1c remains above goal after 3-6 months of basal insulin titration, or when significant postprandial glucose excursions exceed 180 mg/dL (10.0 mmol/L) occur despite adequate basal insulin dosing. 1

Clinical Indicators for Adding Prandial Insulin

Primary Trigger

• Fasting glucose controlled BUT HbA1c remains elevated after 3-6 months of optimized Lantus therapy 1
• Postprandial glucose spikes >180 mg/dL despite target fasting levels 1

Secondary Indicators

• Basal insulin dose approaching or exceeding 0.5 U/kg/day, especially as it nears 1.0 U/kg/day 1
• Large glucose drops occurring overnight or between meals as basal insulin is increased (indicating excessive basal coverage relative to prandial needs) 1
• When further increases in Lantus cause hypoglycemia without improving overall control 1

Stepwise Approach to Adding Humalog

Step 1: Start with One Meal

Add Humalog before the meal causing the largest postprandial glucose excursion - typically the meal with greatest carbohydrate content, often dinner 1

Step 2: Sequential Addition

• Add a second Humalog injection before the meal with the next largest excursion (often breakfast) 1
• Finally add a third injection before the smallest meal (often lunch) if needed 1

Step 3: Adjust Basal Insulin

Simultaneously decrease Lantus dose when initiating prandial insulin to avoid hypoglycemia, particularly if large glucose drops were occurring between meals 1

Dosing Considerations

Humalog Administration

• Inject 0-2 minutes before meals for optimal postprandial control 2
• Humalog provides rapid onset (5 minutes), peaks at 1-2 hours, and lasts 3-4 hours 1
• More effective than regular insulin for controlling postprandial glucose excursions 3

Medication Adjustments

• Discontinue sulfonylureas and meglitinides once prandial insulin is started to avoid hypoglycemia 1
• Consider reducing or stopping thiazolidinediones to minimize edema and weight gain 1
• Metformin can be continued 1

Monitoring Requirements

Glucose Monitoring

• Daily self-monitoring of fasting AND postprandial glucose is essential during titration 1
• Check glucose 2 hours after meals to assess prandial insulin effectiveness 1
• Target postprandial glucose <180 mg/dL 1

Follow-up Assessment

• Reassess HbA1c every 3 months 4
• The glycemic benefits of basal-bolus regimens are generally modest in typical patients, so individualize based on degree of hyperglycemia and patient capacity 1

Important Caveats

Hypoglycemia Risk

• Rapid-acting insulin like Humalog can cause rapid-onset hypoglycemia, giving less time to recognize symptoms 1
• Patients must be educated on recognizing and treating hypoglycemia with 4-8 oz juice or soda, followed by glucose recheck in 15-20 minutes 1
• Glargine (Lantus) has no peak action time and lower hypoglycemia risk than intermediate-acting insulins 1

Patient Capacity

• Basal-bolus therapy requires significant patient education, motivation, and ability to perform multiple daily injections 1
• For elderly patients (≥65-70 years) or those with limited support systems, less intensive regimens may be more appropriate with higher HbA1c targets (7.5-8.0%) 1
• Consider patient's economic status, as rapid-acting analogs are more expensive than regular insulin 1

Expected Outcomes

• The actual glycemic benefits of advancing from basal-only to basal-bolus regimens are generally modest in typical patients 1
• Improved postprandial control is the primary benefit, with variable effects on overall HbA1c 3, 5