What are the recommended adjustments to pump settings for a patient on Tandem Slim X2 (insulin pump) with basal needs of 30 units per day, currently receiving Dexamethasone (corticosteroid) 4 mg every 12 hours?

Pump Settings Adjustment for Dexamethasone-Induced Hyperglycemia

Immediate Basal Rate Adjustment

Based on the insulin drip averaging 7 units/hour (168 units/24 hours), your new total daily basal insulin requirement should be approximately 84 units per day (50% of the IV insulin dose), representing a 180% increase from your baseline 30 units/day. 1

Calculating New Basal Rate

• The American Diabetes Association recommends that when transitioning from IV to subcutaneous insulin, the total subcutaneous dose equals half of the IV insulin infused over 24 hours, with 50% given as basal insulin 2
• Your new basal rate should be 3.5 units/hour (84 units ÷ 24 hours), up from your baseline 1.25 units/hour 1, 3
• This represents the appropriate 150-200% increase in basal insulin needed for high-dose dexamethasone (4 mg BID = 8 mg total daily) 1, 3

Carbohydrate Ratio Adjustments

All carbohydrate ratios should be tightened by approximately 40-50% to account for dexamethasone-induced insulin resistance. 3, 4

• Overnight: Change from 1:10 to 1:6 3
• Breakfast: Change from 1:5 to 1:3 3
• Lunch: Change from 1:8 to 1:5 3
• Dinner: Change from 1:8 to 1:5 3

Research demonstrates that patients on high-dose dexamethasone require 63-77% of their total insulin as prandial coverage, with only 23-37% as basal, reflecting the profound postprandial insulin resistance 4

Insulin Sensitivity Factor (Correction Factor) Adjustments

Your correction factors should be approximately doubled in strength to manage steroid-induced hyperglycemia. 3

• Breakfast: Change from 1:25 to 1:12-15 (more aggressive correction) 3
• Rest of day: Change from 1:50 to 1:25 3

The American Diabetes Association recommends a correction of 1 unit for every 25 mg/dL above target during steroid therapy, representing a significantly more aggressive approach 3

Critical Timing Considerations

These increased settings should be maintained for 24-48 hours after each dexamethasone dose, then rapidly tapered as steroid effects wane. 1

• Dexamethasone causes hyperglycemia that peaks 7-9 hours after administration and persists for at least 24 hours, with effects substantially diminishing by 48 hours 1
• At 48 hours post-dexamethasone: Reduce basal rate by approximately 50% (back toward 1.75-2.0 units/hour) to prevent severe hypoglycemia 1
• At 48 hours: Return carb ratios toward baseline (approximately 30-40% reduction from peak steroid settings) 1

Control IQ Considerations

Maintain Control IQ active, but expect the system to require significant manual overrides during peak steroid effect. 1, 3

• The automated insulin delivery will help prevent hypoglycemia during the rapid decline phase at 24-48 hours post-dose 1
• Monitor glucose every 4-6 hours during steroid therapy, with particular attention to afternoon and evening readings when dexamethasone-induced hyperglycemia peaks 1, 3

Monitoring Requirements

Check blood glucose every 4-6 hours while on dexamethasone, with heightened vigilance at 24-48 hours post-dose when hypoglycemia risk is highest. 1, 3

• The transition from 24 to 48 hours post-dexamethasone is a high-risk period for hypoglycemia if insulin doses are not appropriately reduced 1
• If blood glucose remains >180 mg/dL at 48 hours, maintain current increased settings and reassess in 12 hours 1
• If blood glucose is 100-140 mg/dL at 48 hours, reduce basal rate by 50-60% immediately 1

Common Pitfalls to Avoid

• The most dangerous error is maintaining increased insulin doses beyond 24-48 hours, as this creates severe hypoglycemia risk when steroid effects dissipate 1
• Do not restrict carbohydrate intake to manage hyperglycemia; instead, optimize insulin therapy to avoid malnutrition risk 3
• Insulin requirements can decline rapidly after dexamethasone effects wane, requiring prompt dose adjustments 1, 3

Practical Algorithm Summary

1. Immediately upon starting dexamethasone: Increase basal to 3.5 units/hour, tighten all carb ratios by 40-50%, strengthen correction factors by 50% 1, 3, 4
2. During active steroid effect (0-24 hours): Maintain aggressive settings, monitor every 4-6 hours 1, 3
3. At 24-48 hours post-dose: Begin reducing basal by 50%, loosen carb ratios by 30-40%, return to standard correction factors 1
4. Beyond 48 hours: Return to near-baseline settings with continued monitoring for 72 hours 1