Titrating Basal Insulin Based on Glucose Patterns
No, you should titrate the evening dose of Lantus, not the morning dose, when morning glucose levels are good but evening glucose levels are elevated. This is because basal insulin glargine works over approximately 24 hours to control fasting and between-meal glucose levels, and the dose you give affects the glucose levels measured approximately 24 hours later 1.
Understanding Basal Insulin Pharmacokinetics
Lantus (insulin glargine) has a relatively constant plasma concentration over 24 hours with no pronounced peak, providing steady background insulin coverage 2, 3. The key principle is that the basal insulin dose you administer controls the fasting glucose measured the following morning 1, 4.
- If you give Lantus in the evening (most common timing), it primarily controls your fasting glucose the next morning 5
- The evening glucose levels are controlled by the basal insulin that was given the previous evening (approximately 24 hours earlier) 1
- Morning glucose reflects the adequacy of the previous evening's basal insulin dose 1
Correct Titration Strategy
When morning glucose is at target (80-130 mg/dL) but evening glucose remains elevated, this indicates your current evening Lantus dose is appropriate for overnight coverage but insufficient for daytime coverage 1, 4.
The titration algorithm should be:
- Increase the evening Lantus dose by 2 units every 3 days if evening glucose is 140-179 mg/dL 1
- Increase by 4 units every 3 days if evening glucose is ≥180 mg/dL 1
- Continue titration until evening glucose reaches 80-130 mg/dL 1, 4
Critical Threshold Warning
However, before continuing to escalate basal insulin, you must recognize if you're approaching "overbasalization" 1, 6. Clinical signals include:
- Basal insulin dose exceeding 0.5 units/kg/day 1, 6
- Large bedtime-to-morning glucose differential (≥50 mg/dL drop overnight) 1, 6
- Episodes of hypoglycemia 1
- High glucose variability throughout the day 1
When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, adding prandial insulin becomes more appropriate than continuing to escalate basal insulin alone 1, 6. This is because elevated evening glucose likely reflects postprandial excursions from lunch that basal insulin alone cannot adequately control 6.
Alternative Approach: Adding Prandial Coverage
If your Lantus dose is already substantial (>0.5 units/kg/day) and evening glucose remains elevated despite good morning glucose:
- Start with 4 units of rapid-acting insulin before lunch (or 10% of your current basal dose) 1, 6
- Titrate prandial insulin by 1-2 units every 3 days based on evening glucose readings 1, 6
- Consider adding a GLP-1 receptor agonist to address postprandial hyperglycemia while minimizing hypoglycemia and weight gain 1, 6
Common Pitfall to Avoid
Do not switch to morning Lantus dosing or add a morning dose simply because evening glucose is elevated 1. The timing of Lantus administration (morning, evening, or bedtime) can be flexible and should be based on patient convenience and hypoglycemia patterns, not on which glucose values need improvement 5. Studies show that Lantus is equally effective when given before breakfast, dinner, or bedtime, though nocturnal hypoglycemia occurs less frequently with morning administration 5.