What is the recommended Lantus (insulin glargine) dose, carb ratio, and correction scale for a 67-year-old female patient with type 2 diabetes, A1c 9.7, requiring 3-4 units/hour on insulin drip, with impaired renal function (creatinine 1.22, GFR 48), and sepsis, who has just started eating?

Transitioning from Insulin Drip to Subcutaneous Insulin in Septic Patient with Renal Impairment

For this 67-year-old female with sepsis, renal impairment (GFR 48), and requiring 3-4 units/hour insulin drip, calculate total daily dose (TDD) as 72-96 units/day, then initiate 50-60 units of Lantus daily (60-75% of TDD due to renal dysfunction and sepsis risk) with conservative correction scale, deferring carb ratio until metabolically stable. 1, 2

Calculating Initial Lantus Dose

Step 1: Determine Total Daily Dose from Drip

• Current insulin drip: 3-4 units/hour
• Calculate 24-hour requirement: 3 units/hour × 24 = 72 units; 4 units/hour × 24 = 96 units
• Use conservative estimate of 80 units as baseline TDD 1

Step 2: Adjust for Renal Impairment and Sepsis

Reduce calculated dose by 25-40% due to GFR 48 and acute sepsis, as insulin clearance is impaired and hypoglycemia risk is substantially elevated in this population. 1

• With GFR 48 (Stage 3a CKD), insulin should be "initiated and titrated conservatively to avoid hypoglycemia" 1
• In septic patients, target blood glucose ≤180 mg/dL rather than tighter control to minimize hypoglycemia risk 1, 2
• Recommended starting Lantus dose: 50-60 units once daily (approximately 60-75% of drip TDD) 1

Step 3: Timing and Overlap Strategy

• Administer first Lantus dose in the morning (not bedtime) for easier monitoring 1
• Continue insulin drip for 2-4 hours after first Lantus injection to ensure adequate overlap and prevent rebound hyperglycemia 1
• Monitor blood glucose every 2-4 hours initially until stable 1, 2

Correction Scale (Sliding Scale)

Use conservative correction doses given renal impairment and sepsis:

Simplified Correction Protocol

• Blood glucose 180-250 mg/dL: 2 units rapid-acting insulin 1, 3
• Blood glucose 251-300 mg/dL: 4 units rapid-acting insulin 1, 3
• Blood glucose >300 mg/dL: 6 units rapid-acting insulin and notify provider 3

Critical caveat: Check blood glucose before each correction dose to avoid "insulin stacking" - do not give correction doses more frequently than every 4 hours 3. In renal impairment, insulin action is prolonged, increasing stacking risk 1, 4.

Carbohydrate Ratio: DEFER Initially

Do not establish carb ratio at this time. 1

Rationale for Deferring Carb Ratio

• Patient just started eating - nutritional intake is unstable and unpredictable 1
• Sepsis causes significant insulin resistance variability that will change as infection resolves 5, 6
• Renal impairment affects insulin clearance unpredictably 1, 4
• Use correction scale only for first 3-5 days while monitoring glucose patterns 1

When to Add Prandial Coverage

Once patient is:

• Eating consistently (stable meal intake for 48+ hours) 1
• Metabolically stable (sepsis resolving, no vasopressor requirement) 1, 2
• Requiring consistent correction doses before meals 3

Then initiate prandial insulin at 4 units before largest meal, or 10% of basal dose (5-6 units in this case), adjusting by 1-2 units every 2-3 days based on 2-hour postprandial glucose 3.

Monitoring Protocol

Frequency

• Every 2 hours for first 12-24 hours after transition 1, 2
• Every 4 hours once stable 1, 2
• Use arterial blood samples if arterial line present (more accurate than capillary in sepsis/hypoperfusion states) 2

Target Range

• Goal: 140-180 mg/dL 1, 2
• Avoid targets <140 mg/dL in acute sepsis due to increased hypoglycemia risk without mortality benefit 1, 6

Titration Strategy

• If fasting glucose consistently >150 mg/dL: increase Lantus by 2-4 units every 3 days 1, 3
• If any glucose <80 mg/dL: decrease Lantus by 4 units (or 10-20%) 1, 3
• If requiring >20 units total correction insulin daily: increase Lantus by 20% of correction dose used 3

Critical Safety Considerations

Hypoglycemia Prevention

• Severe hypoglycemia risk is 4-6 times higher with intensive insulin therapy in sepsis 6
• In renal failure, hypoglycemia risk increases substantially - one study showed 76% moderate hypoglycemia rate with aggressive protocols 4
• Ensure bedside glucose tablets/D50 immediately available 1
• Hold insulin if patient NPO or nutrition interrupted 1

Medication Interactions

• Metformin is contraindicated with GFR <45 - ensure this is held 1
• If patient was on sulfonylureas at home, do NOT restart while on insulin (additive hypoglycemia risk) 3

Sepsis-Specific Concerns

• Insulin requirements will likely decrease as sepsis resolves 5, 7
• Anticipate 30-40% reduction in insulin needs over 7-12 days as acute illness improves 7
• Reassess total insulin dose every 2-3 days 1, 3

Common Pitfalls to Avoid

1. Do not use 100% of drip TDD - this causes severe hypoglycemia in renal impairment 1, 4
2. Do not establish carb ratios during acute illness - wait until metabolically stable 1
3. Do not target glucose <140 mg/dL in sepsis - increases mortality risk 1, 6
4. Do not give correction doses more frequently than every 4 hours - causes insulin stacking 3
5. Do not continue drip and subcutaneous insulin simultaneously beyond 2-4 hours - causes severe hypoglycemia 1