Basal Rate Adjustment for Dexamethasone 4 mg BID on Tandem Slim X2
Increase all basal rates by 50-60% across all time periods while the patient is receiving dexamethasone 4 mg every 12 hours, with particular emphasis on afternoon and evening rates where steroid-induced hyperglycemia peaks. 1
Recommended New Pump Settings
Basal Rate Adjustments
Based on guideline recommendations for high-dose dexamethasone, apply a 50-60% increase to all existing basal rates 1, 2:
- 12 am - 7 am: Increase from 0.8 to 1.2-1.3 units/hour 1
- 8 am - 10 am: Increase from 1.7 to 2.6-2.7 units/hour 1
- 11 am - 11:59 am: Increase from 1.5 to 2.3-2.4 units/hour 1
- 12 pm - 5 pm: Increase from 1.1 to 1.7-1.8 units/hour 1, 2
- 6 pm - 11 pm: Increase from 1.5 to 2.3-2.4 units/hour 1, 2
The afternoon and evening periods (12 pm - 11 pm) are particularly critical because dexamethasone causes peak hyperglycemia 7-9 hours after administration, with effects persisting for at least 24 hours 3, 2.
Carbohydrate Ratio Adjustment
Adjust the carbohydrate ratio from current settings to 1:7 or 1:8 (representing a 25-30% increase in mealtime insulin) to counteract steroid-induced insulin resistance. 1 This more aggressive ratio is necessary because dexamethasone impairs beta-cell insulin secretion and increases hepatic gluconeogenesis 3.
Correction Factor (Insulin Sensitivity Factor)
Implement a more aggressive correction scale with rapid-acting insulin every 4-6 hours: 1
- Blood glucose 150-175 mg/dL: 1 unit 1
- Blood glucose 176-200 mg/dL: 2 units 1
- Blood glucose 201-250 mg/dL: 3 units 1
- Blood glucose 251-300 mg/dL: 4 units 1
- Blood glucose >300 mg/dL: 5 units and contact provider 1
This represents approximately 1 unit of rapid-acting insulin for every 25 mg/dL above target glucose 1.
Critical Monitoring Requirements
Check blood glucose every 4-6 hours while on dexamethasone, with particular attention to afternoon and evening readings when hyperglycemia peaks. 1, 2 The Control-IQ technology on the Tandem X2 will provide automated adjustments, but manual monitoring remains essential to ensure adequate control 4.
Duration of Increased Settings
Maintain these increased basal rates for at least 24 hours after each dexamethasone dose. 1, 3 Since the patient is receiving dexamethasone every 12 hours (BID), the elevated insulin requirements will be continuous throughout treatment 2.
Tapering Strategy When Dexamethasone is Discontinued
Begin reducing basal rates back toward baseline 24-48 hours after the last dexamethasone dose, decreasing by 10-20% every 1-2 days while monitoring closely for hypoglycemia. 3 Insulin requirements can decline rapidly after dexamethasone is stopped, creating substantial hypoglycemia risk if doses are not promptly adjusted 3.
The transition period from 24 to 48 hours post-dexamethasone is particularly high-risk for hypoglycemia if insulin doses remain elevated 3.
Common Pitfalls to Avoid
The most dangerous error is maintaining increased insulin doses beyond 24-48 hours after dexamethasone discontinuation, as this creates severe hypoglycemia risk when steroid effects dissipate. 3
Do not restrict carbohydrate intake to manage hyperglycemia—instead optimize insulin therapy to avoid malnutrition risk. 1 This is particularly important for patients on chronic steroid therapy.
If hyperglycemia persists despite the 50-60% basal increase, consider adding NPH insulin in the morning (approximately 0.1-0.3 units/kg) in addition to the increased basal rates. 1, 2 This approach has been shown to significantly improve glycemic control in patients with diabetes already on insulin therapy who receive glucocorticoids 2.
Leveraging Control-IQ Technology
The Control-IQ algorithm on the Tandem X2 will automatically adjust basal insulin delivery and provide correction boluses when glucose is predicted to rise above 180 mg/dL 4. However, the baseline basal rate settings you program are the foundation upon which Control-IQ operates 5. More aggressive correction factor settings have been shown to predict higher time in range with negligible impact on hypoglycemia in real-world Control-IQ users 5.