A patient who started liraglutide (Victoza) 0.6 mg two days ago is on insulin glargine (Lantus) 45 units daily with an insulin‑to‑carbohydrate ratio of 5 g per unit and an insulin sensitivity factor of 15 mg/dL per unit; their blood glucose readings are 212 mg/dL fasting, 240 mg/dL after breakfast (61 g carbohydrate), 218 mg/dL after lunch (60 g carbohydrate), 241 mg/dL after dinner (65 g carbohydrate), and 190 mg/dL at 2 am. What should the insulin glargine dose, insulin‑to‑carbohydrate ratio, and insulin sensitivity factor be adjusted to?

Insulin Dose Adjustments After Starting Liraglutide

Increase Lantus to 50 units daily (approximately 10% increase), tighten the insulin-to-carbohydrate ratio to 1:4 (from 1:5), and adjust the insulin sensitivity factor to 12 mg/dL per unit (from 15). However, given that liraglutide was started only 2 days ago, the more prudent approach is to wait 2-4 weeks before making major insulin adjustments, as liraglutide's full glucose-lowering effect has not yet manifested.

Rationale for Delayed Adjustment

The blood glucose pattern shows persistent hyperglycemia (fasting 212 mg/dL, post-meal peaks 218-241 mg/dL, overnight 190 mg/dL), but you've only been on Victoza 0.6 mg for 2 days. This is critical context:

• Liraglutide requires dose escalation and time to reach full effect 1. The standard protocol starts at 0.6 mg for 1 week, then 1.2 mg for 1 week, before reaching the maintenance dose of 1.8 mg 1, 2.
• Research demonstrates that liraglutide improves insulin sensitivity within 2 weeks, even before weight loss occurs 3, and significantly reduces insulin requirements when combined with basal insulin 1, 4.
• In studies combining liraglutide with basal insulin, patients used approximately 35.8 IU of insulin versus 40.1 IU on placebo after 26 weeks 1, representing a meaningful reduction.

Immediate Management (Next 2-4 Weeks)

Hold off on major Lantus increases. Instead:

Basal Insulin (Lantus)

• Keep Lantus at 45 units for now or make only a modest increase to 47-48 units (4-7% increase) if fasting glucose remains >200 mg/dL after 1 week on liraglutide 1.2 mg
• The fasting glucose of 212 mg/dL and 2 AM glucose of 190 mg/dL suggest inadequate basal coverage, but this will likely improve as liraglutide is titrated up
• According to ADA guidelines, increase basal insulin by 2 units every 3 days to reach fasting plasma glucose goal without hypoglycemia 5

Prandial Coverage

Your current insulin-to-carbohydrate ratio (ICR) of 1:5 means:

• Breakfast: 61g ÷ 5 = 12.2 units → BG rose from 212 to 240 (28 mg/dL rise)
• Lunch: 60g ÷ 5 = 12 units → BG dropped from 240 to 218 (22 mg/dL fall)
• Dinner: 65g ÷ 5 = 13 units → BG rose from 218 to 241 (23 mg/dL rise)

Tighten ICR modestly to 1:4.5 (meaning 1 unit per 4.5g carbohydrate) for now:

• This represents approximately a 10% increase in prandial insulin
• Re-evaluate after liraglutide reaches 1.8 mg maintenance dose

Insulin Sensitivity Factor (ISF)

Your current ISF of 15 means 1 unit drops glucose by 15 mg/dL.

Adjust ISF to 12-13 mg/dL per unit for correction doses:

• This makes corrections more aggressive given persistent hyperglycemia
• Monitor closely for hypoglycemia as liraglutide effect increases

After Liraglutide Reaches Maintenance Dose (Week 3-4)

Once you've been on liraglutide 1.8 mg for at least 1-2 weeks:

Expected Changes

• Insulin requirements typically decrease by 15-25% when liraglutide is added to basal insulin 1, 4
• Fasting glucose should improve by approximately 1.3 mmol/L (23 mg/dL) 1
• Post-prandial glucose excursions should decrease 1, 2

Reassess and Adjust

At that point, if glucose remains elevated:

• Increase Lantus by 2 units every 3 days targeting fasting glucose 80-130 mg/dL 5
• Further tighten ICR to 1:4 if post-prandial glucose remains >180 mg/dL
• Adjust ISF to 10-12 if corrections are inadequate

Critical Pitfalls to Avoid

1. Don't aggressively increase insulin in the first 2-3 weeks of liraglutide therapy - you risk hypoglycemia as the GLP-1 effect kicks in 1, 4
2. Monitor for hypoglycemia closely - liraglutide increases minor hypoglycemia risk (18.2% vs 12.4% placebo) when combined with insulin 1
3. Expect gastrointestinal side effects - nausea occurs in ~22% of patients 1, 2 but is typically transient
4. If hypoglycemia occurs without clear cause, reduce the corresponding insulin dose by 10-20% 5

Monitoring Plan

• Check fasting glucose daily
• Check pre-meal and 2-hour post-meal glucose at least once daily (rotating meals)
• Reassess insulin doses weekly during liraglutide titration
• Once stable on liraglutide 1.8 mg, reassess every 3-6 months 5

The combination of liraglutide and basal insulin is evidence-based and effective 1, 6, 2, but patience during the titration phase prevents dangerous hypoglycemia while allowing the full synergistic benefit to emerge.