Increase Lantus to 20 Units in the Morning
For a patient with an average fasting glucose of 106 mg/dL who experienced a 9 AM spike to 300 mg/dL, the priority is to increase the mealtime insulin (Humalog) rather than the basal insulin (Lantus), because the 9 AM reading reflects inadequate breakfast coverage, not basal insufficiency. However, given the fasting glucose averaging 106 mg/dL (target 80–130 mg/dL), a modest basal increase is also reasonable.
Understanding the Problem
Fasting glucose of 106 mg/dL indicates adequate basal insulin coverage, as the target fasting range is 80–130 mg/dL, and this patient is already within that range 1.
A 9 AM glucose spike to 300 mg/dL reflects inadequate prandial (mealtime) insulin at breakfast, not a basal insulin problem 1, 2. The 9 AM reading occurs 2–3 hours after breakfast and is controlled by the Humalog dose given before that meal, not by Lantus 1.
Basal insulin (Lantus) controls fasting and between-meal glucose levels by suppressing hepatic glucose production overnight and between meals—it does not address postprandial excursions 1, 2.
Recommended Management Algorithm
Step 1: Increase Breakfast Humalog Immediately
Increase the breakfast Humalog dose by 2 units (from 4–6 units to 6–8 units) and titrate by 1–2 units every 3 days based on the 2-hour post-breakfast glucose reading 1.
Target post-breakfast glucose <180 mg/dL 1.
A 9 AM glucose of 300 mg/dL clearly indicates the current breakfast insulin dose is insufficient 1, 2.
Step 2: Modest Basal Insulin Adjustment (Optional)
If fasting glucose consistently exceeds 110 mg/dL on multiple days, increase Lantus by 1–2 units (from 18 to 19–20 units) 1.
Do not increase Lantus beyond 0.5 units/kg/day without addressing prandial coverage 1. For most adults, this threshold is approximately 35–40 units; at 18 units, this patient is well below that limit 1.
Titrate Lantus by 2 units every 3 days if fasting glucose is 140–179 mg/dL, or by 4 units every 3 days if ≥180 mg/dL 1.
Step 3: Add Correction Insulin for High Pre-Meal Readings
For pre-meal glucose >250 mg/dL, add 2 units of Humalog as a correction dose in addition to the scheduled meal dose 1.
For pre-meal glucose >350 mg/dL, add 4 units of Humalog 1.
Correction insulin is an adjunct to scheduled prandial insulin, not a replacement 1.
Why Not Increase Lantus Alone?
Increasing basal insulin to address a 9 AM spike leads to "overbasalization," a dangerous pattern where excessive basal insulin masks the need for mealtime coverage 1, 2.
Clinical signals of overbasalization include:
Continuing to escalate Lantus beyond 0.5–1.0 units/kg/day without addressing postprandial hyperglycemia leads to suboptimal control and increased hypoglycemia risk 1.
Monitoring and Titration
Check fasting glucose daily to guide Lantus adjustments 1.
Check 2-hour post-breakfast glucose to assess adequacy of breakfast Humalog and guide further titration 1.
Reassess every 3 days during active titration and adjust doses accordingly 1.
Adjunctive Therapy Considerations
Ensure the patient is on metformin unless contraindicated, as metformin reduces total insulin requirements by 20–30% and provides superior glycemic control when combined with insulin 1.
Empagliflozin (Jardiance) 25 mg is already on board, which provides additional glucose-lowering through urinary glucose excretion and may reduce insulin requirements by approximately 10–15% 3, 4, 5.
Common Pitfalls to Avoid
Do not rely solely on increasing Lantus to fix a 9 AM spike—this reflects inadequate breakfast coverage, not basal insufficiency 1, 2.
Do not delay adding or increasing prandial insulin when postprandial glucose consistently exceeds 250 mg/dL 1.
Do not give rapid-acting insulin (Humalog) at bedtime as a sole correction dose, as this markedly increases nocturnal hypoglycemia risk 1.
Hypoglycemia Management
Treat any glucose <70 mg/dL immediately with 15 g of fast-acting carbohydrate, recheck in 15 minutes, and repeat if needed 1.
If hypoglycemia occurs without an obvious cause, reduce the implicated insulin dose by 10–20% immediately 1.
The patient reports being symptomatic below 100 mg/dL, which may indicate hypoglycemia unawareness or a lower personal threshold—educate on recognizing and treating glucose <70 mg/dL 1.