How do I adjust Lantus (insulin glargine) dosing for patients with hyperglycemia?

Adjusting Lantus for High Blood Sugars

Increase your Lantus dose by 2 units every 3 days if fasting glucose is 140-179 mg/dL, or by 4 units every 3 days if fasting glucose is ≥180 mg/dL, until fasting blood glucose reaches 80-130 mg/dL. 1

Initial Assessment: Determine What Type of Hyperglycemia You're Treating

Before adjusting Lantus, identify whether the elevated blood sugars are:

• Fasting/pre-meal hyperglycemia → Increase basal insulin (Lantus) 1
• Post-meal hyperglycemia → Add prandial (mealtime) insulin, NOT more Lantus 1, 2

This distinction is critical because continuing to escalate Lantus for post-meal highs leads to "overbasalization"—a dangerous pattern of excessive basal insulin that causes hypoglycemia between meals while failing to control post-meal spikes. 2, 3

Standard Titration Algorithm for Fasting Hyperglycemia

Follow this evidence-based protocol: 1

• If fasting glucose 140-179 mg/dL: Increase Lantus by 2 units every 3 days 1
• If fasting glucose ≥180 mg/dL: Increase Lantus by 4 units every 3 days 1
• Target: Fasting blood glucose 80-130 mg/dL 1, 2
• If hypoglycemia occurs: Reduce dose by 10-20% immediately 1

Alternatively, you can use a 10-15% dose increase once or twice weekly until target is reached. 1, 2

Critical Threshold: When to STOP Increasing Lantus

Do not continue escalating Lantus beyond 0.5 units/kg/day without adding prandial insulin. 1, 2, 3 When basal insulin approaches 0.5-1.0 units/kg/day and glucose remains elevated, further increases in Lantus lead to overbasalization rather than improved control. 2

Clinical Signs You've Reached the Lantus Limit:

• Basal insulin dose >0.5 units/kg/day 2, 3
• Bedtime-to-morning glucose differential ≥50 mg/dL 2, 3
• Hypoglycemia episodes 2, 3
• High glucose variability 2, 3
• Fasting glucose controlled but A1C remains elevated after 3-6 months 1, 2

Adding Prandial Insulin When Lantus Alone Is Insufficient

If blood sugars remain in the 200s mg/dL despite adequate Lantus titration, you need mealtime insulin, not more Lantus. 3 This reflects both inadequate basal coverage AND postprandial excursions. 3

How to Add Prandial Insulin:

• Start with 4 units of rapid-acting insulin before the largest meal (or 10% of current basal dose) 1, 2, 3
• Increase prandial insulin by 1-2 units or 10-15% every 3 days based on post-meal glucose readings 2
• Add to additional meals as needed based on glucose patterns 1

Monitoring Requirements During Titration

• Daily fasting blood glucose monitoring is essential during active dose adjustments 2
• Reassess insulin adequacy at every clinical visit 1, 2
• Look specifically for signs of overbasalization at each assessment 2
• Adjust doses every 3 days during titration phase 1, 2

Common Pitfalls to Avoid

Never continue escalating Lantus beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to suboptimal control and increased hypoglycemia risk. 2, 3

Don't delay adding prandial insulin when signs of overbasalization appear—blood glucose in the 200s mg/dL on substantial Lantus doses (e.g., 38+ units) indicates significant insulin deficiency that requires mealtime coverage, not just more basal insulin. 3

Always verify the patient remains on metformin (unless contraindicated) when intensifying insulin therapy—it remains the foundation of type 2 diabetes treatment. 2, 3

Don't wait longer than 3 days between dose adjustments in stable patients, as this unnecessarily prolongs time to glycemic targets. 2

Alternative: Consider GLP-1 Receptor Agonist

If A1C remains above goal despite optimized basal insulin, consider adding a GLP-1 receptor agonist to the regimen instead of or in addition to prandial insulin to improve A1C while minimizing weight gain and hypoglycemia risk. 1, 3

Special Situations Requiring Modified Dosing

For hospitalized patients on high-dose home insulin (≥0.6 units/kg/day): Reduce total daily dose by 20% upon admission to prevent hypoglycemia. 2

For high-risk patients (elderly >65 years, renal failure, poor oral intake): Use lower doses of 0.1-0.25 units/kg/day. 2

For steroid-induced hyperglycemia: Add 0.1-0.3 units/kg/day of Lantus to the usual insulin regimen, with doses determined by steroid dose and oral intake. 2