Insulin Adjustment for Dexamethasone-Induced Hyperglycemia
For this 67-year-old male with BMI 40 who received dexamethasone 10 mg yesterday, the Lantus dose should be increased to approximately 98 units (150% of baseline 65 units), with a carbohydrate ratio of 1:8 (from 1:10) and a correction scale of 1 unit for every 25 mg/dL above target glucose. 1, 2
Lantus (Basal Insulin) Adjustment
- Dexamethasone causes significant hyperglycemia with effects persisting for at least 24 hours after administration, characterized by afternoon and evening hyperglycemia 1, 2
- For patients receiving high-dose dexamethasone (10 mg), increase basal insulin by approximately 50% of the baseline dose 1, 2
- For this patient:
- Current Lantus dose: 65 units
- Recommended adjusted dose: 98 units (150% of baseline) 2
- Maintain this higher dose for at least 24 hours after dexamethasone administration 2, 3
- After steroid effects diminish (typically 1-2 days after a single dose), gradually taper back to baseline dose while monitoring blood glucose levels 2, 3
Carbohydrate Ratio Adjustment
- Current carbohydrate ratio: 1:10 (1 unit of insulin for every 10g of carbohydrate)
- Recommended adjusted ratio: 1:8 (approximately 20-25% increase in insulin) 2
- This adjustment accounts for the increased insulin resistance caused by dexamethasone 2, 3
- Maintain this adjusted carb ratio for 24-48 hours after dexamethasone administration 2
Correction Scale (Insulin Sensitivity Factor)
- For steroid-induced hyperglycemia, a more aggressive correction scale is needed 1
- Recommended correction: 1 unit of rapid-acting insulin for every 25 mg/dL above target glucose 1, 2
- Example correction scale:
- Blood glucose 150-175 mg/dL: 1 unit
- Blood glucose 176-200 mg/dL: 2 units
- Blood glucose 201-250 mg/dL: 3 units
- Blood glucose 251-300 mg/dL: 4 units
- Blood glucose >300 mg/dL: 5 units and call provider 1
Monitoring Recommendations
- Check blood glucose every 4-6 hours while the patient is affected by dexamethasone 1, 2
- Pay particular attention to afternoon and evening glucose levels, as steroid-induced hyperglycemia tends to be more pronounced during these times 1, 4
- Continuous glucose monitoring (CGM) data shows a triphasic glycemic pattern following dexamethasone administration: initial hyperglycemia, transient improvement, followed by another hyperglycemic plateau 4
Important Considerations
- Dexamethasone-induced hyperglycemia is often poorly controlled with standard insulin regimens 5
- The patient's high BMI (40) and weight (130 kg) suggest significant insulin resistance at baseline, which will be exacerbated by dexamethasone 3
- NPH insulin may be particularly effective for steroid-induced hyperglycemia due to its peak action aligning with the steroid's hyperglycemic effect, but Lantus can be effective with appropriate dose adjustment 5
- If hyperglycemia persists despite increased basal insulin, consider adding NPH insulin in the morning (approximately 0.1-0.3 units/kg) in addition to the Lantus 1
- Monitor for rapid decline in insulin requirements as dexamethasone effects wane to avoid hypoglycemia 1, 2