How should I adjust my insulin glargine (Lantus) dose, currently 10 units in the morning and 4 units in the evening, given fasting hyperglycemia (~200 mg/dL) and pre‑lunch glucose falling to 60‑100 mg/dL?

Adjust Your Lantus Dosing Schedule

You need to consolidate your split-dose Lantus into a single daily injection and reduce the morning dose, because your current twice-daily regimen is causing dangerous mid-day hypoglycemia while failing to control your fasting glucose.

The Core Problem

Your pattern reveals a critical dosing error: Lantus (insulin glargine) is designed as a once-daily basal insulin with a 24-hour duration of action 1. By splitting it into morning and evening doses (10 units AM + 4 units PM = 14 units total), you're creating overlapping insulin peaks that drive your glucose dangerously low by noon (60-100 mg/dL), while the morning dose wears off before the next morning, leaving you with fasting hyperglycemia around 200 mg/dL.

Immediate Action Plan

Step 1: Switch to Once-Daily Dosing

• Stop the split dosing immediately
• Start with 10 units once daily at bedtime (not your current total of 14 units—the morning dose was causing your noon lows) 2
• Choose a consistent time you can maintain every day 1

Step 2: Titrate Using the Evidence-Based Algorithm

Following the 2025 ADA Standards 2:

• Check your fasting blood glucose every morning
• Adjust your dose every 3 days based on the average of your last 3 fasting readings:
  • If FBG ≥180 mg/dL (≥10 mmol/L): increase by 6-8 units
  • If FBG 140-179 mg/dL (7.8-9.9 mmol/L): increase by 4 units
  • If FBG 120-139 mg/dL (6.7-7.7 mmol/L): increase by 2 units
  • If FBG 100-119 mg/dL (5.6-6.6 mmol/L): increase by 0-2 units
  • If FBG <100 mg/dL (<5.6 mmol/L): no change needed
  • If any glucose reading <70 mg/dL (<4.0 mmol/L): decrease dose by 10-20% 2

Step 3: Monitor for Hypoglycemia

• Test your blood glucose before each meal and at bedtime for the first 2 weeks 1
• Your noon readings should normalize to 100-140 mg/dL once the overlapping morning dose is eliminated
• If you experience any reading <70 mg/dL, reduce your Lantus dose by 2-3 units immediately 2

Why This Works

Research demonstrates that once-daily Lantus provides stable 24-hour basal coverage 3. Your twice-daily split was never indicated—studies show morning, dinner, or bedtime administration are all effective, but the key is once-daily dosing 3, 4. The morning administration in your case was stacking insulin action during mid-day when you don't need it, while leaving you uncovered during the dawn phenomenon (3 AM-8 AM) when your liver increases glucose production 5.

Critical Pitfalls to Avoid

• Never mix or dilute Lantus with other insulins—it will not work properly 1
• Don't be timid with dose increases—your FBG of 200 mg/dL requires aggressive titration. You'll likely need 20-30 units once daily based on typical requirements 6, 7, 8
• Don't skip the 3-day waiting period between adjustments—insulin glargine takes 2-4 days to reach steady state
• Rotate injection sites (abdomen, thigh, upper arm) within the same body region to prevent lipohypertrophy 1

Expected Timeline

• Days 1-3: Your noon lows should resolve immediately once you stop the morning dose
• Weeks 1-3: Your fasting glucose should progressively improve as you titrate upward every 3 days
• Week 4-6: You should reach your fasting glucose goal of <100 mg/dL 2

When to Seek Help

Contact your healthcare provider immediately if:

• You experience glucose <60 mg/dL despite dose reductions
• Your fasting glucose remains >180 mg/dL after reaching 0.5 units/kg/day (roughly 35-40 units for most adults)
• You develop symptoms of hyperglycemia (excessive thirst, urination, blurred vision)

Consider obtaining a glucagon emergency kit for severe hypoglycemia risk 2.