What should the Lantus dose, carb ratio, and correction scale be for an elderly male patient with BMI 33, HbA1C 7.5, and impaired renal function, on Lantus, Victoza, metformin, Amaryl, and Jardiance, who received dexamethasone and has post-operative ileus on a clear liquid diet?

Insulin Management for Elderly Patient Post-Dexamethasone with Ileus on Clear Liquids

Immediate Insulin Regimen Modifications

For this elderly patient with post-operative ileus on clear liquids who received dexamethasone 24 hours ago, discontinue all oral diabetes medications immediately and reduce Lantus to 50% of current total daily dose (35 units total: 12.5 units AM, 22.5 units PM), while implementing correction-only rapid-acting insulin for glucose >180 mg/dL. 1, 2

Rationale for Medication Discontinuation

• Stop metformin, Amaryl (glimepiride), and Jardiance immediately due to NPO/clear liquid status and post-operative ileus risk 1
• Continue Victoza 0.6 mg daily only if patient tolerates clear liquids without nausea/vomiting, as GLP-1 agonists can delay gastric emptying and worsen ileus 1
• Discontinue sulfonylurea (Amaryl) to prevent severe hypoglycemia in setting of poor oral intake 1, 2

Basal Insulin Dosing Strategy

Current total Lantus dose: 70 units/day (25 AM + 45 PM)

For this 108 kg patient on clear liquids with ileus:

• Reduce total daily Lantus by 50% to 35 units/day (approximately 0.32 units/kg/day) 2, 3
• Split as: 12.5 units in AM, 22.5 units in PM (maintaining approximate 1:2 ratio) 2
• This reduction accounts for: poor oral intake, post-operative state, and elderly status (high-risk for hypoglycemia) 2, 3

Dexamethasone Impact on Insulin Requirements

Dexamethasone 4 mg given 24 hours ago will cause hyperglycemia for 24-48 hours post-administration:

• Expect 40-60% increase in prandial/correction insulin needs during steroid effect period 2
• Do NOT increase basal insulin for steroid-induced hyperglycemia—address with correction doses only 2
• Peak hyperglycemic effect occurs 8-12 hours post-dose, so patient is currently in peak effect window 2

Correction Scale (NOT Carb Ratio—Patient on Clear Liquids)

Since patient is on clear liquids with minimal carbohydrate intake, use correction-only insulin protocol:

Simplified Correction Scale Using Rapid-Acting Insulin (Humalog/Novolog/Apidra)

Check glucose before each meal and bedtime:

• Glucose 180-250 mg/dL: Give 2 units rapid-acting insulin 2
• Glucose 251-350 mg/dL: Give 4 units rapid-acting insulin 2
• Glucose >350 mg/dL: Give 6 units rapid-acting insulin 2
• Glucose <180 mg/dL: No correction insulin needed 2

Critical Safety Rule: NEVER give rapid-acting insulin at bedtime unless glucose >300 mg/dL due to nocturnal hypoglycemia risk 2

Insulin Sensitivity Factor Calculation

For this patient with estimated total daily dose of 35 units basal + correction doses:

• Insulin Sensitivity Factor (ISF) = 1500 ÷ Total Daily Dose 2
• Estimated ISF = 1500 ÷ 40 = approximately 38 mg/dL per unit 2
• This means 1 unit of rapid-acting insulin should lower glucose by approximately 38 mg/dL 2

Why Carbohydrate Ratio is NOT Applicable

Carbohydrate-to-insulin ratios are ONLY used when patients are eating regular meals with quantifiable carbohydrate content 2. For patients on clear liquids:

• Clear liquid diets should provide 200g carbohydrate/day in equally divided amounts 1
• Liquids should NOT be sugar-free—patients require carbohydrate and calories 1
• Use correction insulin only, not carbohydrate coverage, until patient advances to solid food 1, 2

Monitoring Requirements

Check point-of-care glucose:

• Every 4-6 hours minimum due to poor oral intake 2, 3
• Before each meal attempt and at bedtime 2, 3
• Target glucose range: 140-180 mg/dL for hospitalized non-critically ill elderly patient 2, 3

Advancing Diet and Insulin Adjustments

When patient advances from clear liquids to solid food:

1. Resume metformin 500 mg BID when eating regular diet (hold Amaryl permanently due to hypoglycemia risk in elderly) 1
2. Gradually increase Lantus back toward pre-hospitalization doses by 10-15% every 3 days based on fasting glucose 2
3. Initiate carbohydrate-to-insulin ratio when eating regular meals: Start with 1:10 ratio (1 unit per 10g carbohydrate) 2
4. Resume Jardiance 25 mg daily when stable on oral diet 1

Critical Pitfalls to Avoid

• NEVER use sliding scale insulin as monotherapy—this patient needs scheduled basal insulin 2
• NEVER give rapid-acting insulin at bedtime except for severe hyperglycemia (>300 mg/dL) 2
• NEVER continue sulfonylureas in hospitalized elderly with poor oral intake—severe hypoglycemia risk 1, 2
• NEVER use sugar-free liquids—patients on clear liquids require carbohydrate and calories 1
• NEVER delay reducing insulin doses in patients with decreased oral intake—this causes severe hypoglycemia 2, 3

Special Considerations for This Elderly Patient

Age-related factors requiring conservative approach:

• BMI 33 with Cr 0.94 suggests adequate renal function, but elderly status warrants lower insulin doses 2, 4
• HbA1c 7.5% is at target for elderly patient with complex health status (post-operative, multiple medications) 1, 5
• Hemoglobin 11 g/dL suggests possible chronic disease/malnutrition—avoid aggressive glucose lowering 1, 6
• Target glucose 140-180 mg/dL is appropriate for this elderly hospitalized patient 1, 2