Insulin Management for a 62-Year-Old Female on Dexamethasone with Poor Oral Intake
Recommended Lantus Dose: Increase to 12-16 units once daily
Given this patient's dexamethasone exposure (8 mg), which significantly increases insulin resistance, and her poor oral intake creating hypoglycemia risk, I recommend increasing her Lantus from 8 units to 12-16 units once daily, administered at the same time each day. 1, 2
Rationale for Dose Adjustment:
Dexamethasone effect: 8 mg dexamethasone causes substantial hyperglycemia, typically requiring 50-100% increase in insulin requirements, though this patient's poor oral intake partially offsets this need 1
Current total daily insulin: Her home regimen totals 44 units/day (8 units Lantus + 36 units Novolog), which equals 0.65 units/kg/day for her 68 kg weight 1
Basal insulin proportion: Her current basal insulin (8 units) represents only 18% of total daily dose, which is suboptimal; basal insulin should typically comprise 40-50% of total daily insulin 1, 2
Starting point calculation: 40-50% of 44 units = 18-22 units, but given poor oral intake, start conservatively at 12-16 units to avoid hypoglycemia 3, 1
Titration Protocol:
- Monitor fasting blood glucose daily 1, 2
- If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days 1
- If fasting glucose 140-179 mg/dL: increase by 2 units every 3 days 1
- Target fasting glucose: 100-200 mg/dL given her poor oral intake and acute illness 3
Carbohydrate Ratio: Hold or Use 1:10 Ratio with Extreme Caution
With poor oral intake, do NOT use scheduled mealtime insulin with carbohydrate counting. Instead, give rapid-acting insulin AFTER meals based on actual carbohydrate consumed. 3
Modified Approach for Poor Oral Intake:
Discontinue scheduled Novolog 12 units TID - this is dangerous with unpredictable eating 3
If patient eats: Administer rapid-acting insulin AFTER the meal, dosing 1 unit per 10 grams of carbohydrate actually consumed (1:10 ratio based on her home regimen of ~12 units covering ~120g carbohydrate meals) 3
If patient does not eat: Do NOT give mealtime insulin 3
Critical pitfall: Giving scheduled mealtime insulin with poor oral intake is the leading cause of severe hypoglycemia in hospitalized patients 3
Correction Scale: Use Conservative Sliding Scale
Implement the following correction scale using rapid-acting insulin (Novolog), checking blood glucose before meals and at bedtime: 3, 1
Recommended Correction Factor: 1 unit per 50 mg/dL above target
| Blood Glucose | Correction Dose |
|---|---|
| <100 mg/dL | Hold insulin, give 15g carbohydrate [3] |
| 100-200 mg/dL | 0 units (target range for poor oral intake) [3] |
| 201-250 mg/dL | 1 unit [1] |
| 251-300 mg/dL | 2 units [1] |
| 301-350 mg/dL | 3 units [1] |
| 351-400 mg/dL | 4 units [1] |
| >400 mg/dL | 5 units and notify provider [3] |
Calculation Basis:
- Her estimated insulin sensitivity factor: 1500 ÷ 44 (total daily dose) = ~34 mg/dL per unit 1
- Using conservative 1:50 ratio (rather than 1:34) given poor oral intake and acute illness to minimize hypoglycemia risk 3
Critical Monitoring Parameters
Hypoglycemia Alert Strategy:
- Call provider immediately: Blood glucose <70 mg/dL 3
- Call as soon as possible:
Special Considerations for Dexamethasone:
- Dexamethasone 8 mg typically causes peak hyperglycemia 8-12 hours post-dose 1
- If dexamethasone is discontinued, insulin requirements will drop significantly within 24-48 hours - reduce Lantus by 20-30% at that time 1, 2
- Monitor for steroid-induced hyperglycemia pattern: relatively normal fasting glucose but severe postprandial hyperglycemia 1
Common Pitfalls to Avoid
Do NOT continue scheduled mealtime insulin with poor oral intake - this causes severe hypoglycemia 3
Do NOT rely on A1C for glucose management in acute illness 3
Do NOT use tight glycemic targets (80-130 mg/dL) in this setting; accept 100-200 mg/dL given poor oral intake 3
Do NOT forget basal insulin even when patient is NPO - she still needs basal coverage, though potentially at reduced dose 3, 2
Do NOT mix or dilute Lantus with other insulins 2
Rotate injection sites to avoid lipodystrophy which can cause erratic absorption 2