How to Calculate Lantus Dose
For an 88-year-old man with type 2 diabetes (weight ~80 kg, fasting glucose ~300 mg/dL), start with 16 units of Lantus once daily (0.2 units/kg), then titrate by 2 units every 3 days until fasting glucose reaches 90-150 mg/dL.
Initial Dosing Strategy
Given this patient's severe hyperglycemia (fasting glucose ~300 mg/dL), insulin is the appropriate first-line injectable therapy 1. The current guidelines provide two weight-based starting approaches:
Starting Dose Options:
- Standard approach: 10 units once daily OR 0.1-0.2 units/kg/day 2, 3
- For severe hyperglycemia (glucose ≥300 mg/dL): Use the higher end of the range at 0.2-0.3 units/kg 1
For this 80 kg patient with glucose of 300 mg/dL, calculate:
- 0.2 units/kg × 80 kg = 16 units once daily as the starting dose
This higher starting dose (0.2 units/kg vs 0.1 units/kg) is supported by evidence showing it achieves glycemic targets faster without increasing hypoglycemia risk in patients with elevated baseline glucose 4.
Titration Algorithm
Use a fixed-regimen approach 1:
Every 2-5 Days, Adjust Based on Fasting Glucose:
- FBG >180 mg/dL: Increase by 4 units (or 20% of total daily dose)
- FBG 140-180 mg/dL: Increase by 2 units (or 10% of total daily dose)
- FBG 110-139 mg/dL: Increase by 1 unit
- FBG 90-110 mg/dL: No change (at goal)
- FBG <70 mg/dL: Decrease by 10-20% of total daily dose
The most recent ADA guidelines recommend increasing by 2 units every 3 days as a simple, evidence-based approach 2. The AACE algorithm provides more granular adjustments based on the degree of hyperglycemia 1.
Target Fasting Glucose
For this 88-year-old patient, target fasting glucose of 90-150 mg/dL (5.0-8.3 mmol/L) 5, 6. This relaxed target is appropriate given:
- Advanced age (88 years)
- Risk of hypoglycemia with tighter control
- Likely presence of comorbidities
The standard target of <110 mg/dL used in younger, healthier patients 1 should be liberalized in older adults to minimize hypoglycemia risk while still achieving meaningful glycemic improvement 5.
Administration Details
- Timing: Once daily at the same time each day, can be any time but typically bedtime or morning 3
- Route: Subcutaneous only (abdomen, thigh, or deltoid) - rotate sites within same region 3
- Do NOT: Mix with other insulins, dilute, administer IV, or use in insulin pumps 3
Monitoring and Safety
Essential Monitoring:
- Check fasting glucose daily during titration phase
- Assess for hypoglycemia symptoms (glucose <70 mg/dL requires dose reduction) 1
- Recheck HbA1c at 3 months 2
Hypoglycemia Management:
- If glucose <70 mg/dL: Reduce dose by 10-20% 1
- If glucose <40 mg/dL: Reduce dose by 20-40% 1
- Prescribe glucagon for emergency use 2
When to Intensify Beyond Basal Insulin
If after titrating to 0.5 units/kg/day (~40 units for this patient) the HbA1c remains above goal, consider:
- Adding a GLP-1 receptor agonist (preferred) 2, 7
- Adding prandial insulin with largest meal (start 4 units or 10% of basal dose) 2, 1
Avoid overbasalization - continuing to increase basal insulin beyond 0.5 units/kg/day without achieving fasting glucose goals suggests need for additional therapy rather than further basal insulin escalation 2, 8.
Special Considerations for Older Adults
For this 88-year-old patient:
- Consider morning dosing instead of bedtime to reduce nocturnal hypoglycemia risk 5, 6
- Ensure patient/caregiver can safely draw up and inject insulin
- Simplify regimen if cognitive or functional impairment present 5, 6
- Consider cost - NPH insulin may be more affordable alternative if long-acting analogs are prohibitively expensive 2, 8