In a patient on insulin glargine (Lantus) 11 U basal with a 1 U per 10 g carbohydrate ratio and a medium correction factor, stable renal function, poor oral intake, and receiving 4 mg dexamethasone, how should the basal dose, carbohydrate ratio, and correction scale be adjusted?

Insulin Adjustment for Dexamethasone-Induced Hyperglycemia with Poor Oral Intake

Reduce Lantus to 16–18 units once daily (approximately 50–60% of the current 28-unit dose), return the carbohydrate ratio to 1:10, and use a standard correction scale rather than the high-dose scale. 1, 2

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Immediate Basal Insulin Reduction

• Decrease Lantus from 28 units to 16–18 units (approximately 50–60% reduction) because dexamethasone's hyperglycemic effect substantially diminishes by 48 hours, and maintaining the elevated dose creates severe hypoglycemia risk. 1, 2
• The peak steroid effect occurs 7–9 hours after administration and persists for at least 24 hours, but effects substantially diminish by 48 hours; insulin requirements decline rapidly once the steroid effect wanes. 1, 2
• Poor oral intake further amplifies hypoglycemia risk, necessitating more aggressive dose reduction than would be required with normal intake. 3
• If fasting glucose consistently falls below 100 mg/dL or any hypoglycemic episode occurs, reduce the basal dose by an additional 10–20% (e.g., from 18 units to approximately 14–16 units). 1

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Carbohydrate Ratio Adjustment

• Return the carbohydrate ratio from 1:6 to 1:10 (representing a 40% reduction in mealtime insulin) as insulin resistance normalizes after the steroid effect dissipates. 2
• The 1:6 ratio was appropriate during peak steroid effect (0–24 hours post-dexamethasone) but is now excessive and will cause hypoglycemia. 2
• With poor oral intake, consider using an even more conservative ratio of 1:12 or holding scheduled prandial insulin entirely and relying only on correction doses when glucose exceeds 180 mg/dL. 3
• Monitor pre-meal and 2-hour post-meal glucose levels to fine-tune this ratio over the next 24 hours. 2

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Correction Scale Modification

• Switch from the high correction scale to a standard correction scale because insulin sensitivity is returning to baseline. 2
• Use correction insulin every 4–6 hours as needed, but expect significantly less need for corrections compared to the first 24 hours post-dexamethasone. 2
• For pre-meal glucose >250 mg/dL, add 2 units of rapid-acting insulin; for glucose >350 mg/dL, add 4 units. 3
• With poor oral intake, use correction doses only when glucose exceeds 180 mg/dL to minimize hypoglycemia risk. 3

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Critical Monitoring Requirements

• Check blood glucose every 4–6 hours for the next 24–48 hours, with particular attention to overnight and fasting values when hypoglycemia risk is highest. 1, 2
• The transition from 24 to 48 hours post-dexamethasone is a high-risk period for hypoglycemia if insulin doses are not appropriately reduced. 2
• Continue monitoring for 72 hours total, as dexamethasone is a long-acting glucocorticoid and some residual effect may persist beyond 48 hours. 2
• For patients with poor oral intake, check glucose every 4–6 hours rather than only before meals, as meal timing may be irregular. 3

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Algorithmic Approach to Dose Titration

• If blood glucose remains >180 mg/dL at 48 hours: maintain current Lantus at 16–18 units and reassess in 12 hours. 2
• If blood glucose is 100–140 mg/dL at 48 hours: reduce Lantus to 14–16 units (approximately 50% of the original 28-unit dose). 2
• If blood glucose falls <70 mg/dL: treat with 15 g of fast-acting carbohydrate (if able to take orally), recheck in 15 minutes, and reduce the implicated insulin dose by 10–20% immediately. 3, 2
• If fasting glucose consistently falls below 180 mg/dL: begin tapering Lantus back toward the pre-dexamethasone baseline of 11 units, decreasing by 10–20% every 1–2 days while monitoring closely. 1, 2

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Special Considerations for Poor Oral Intake

• Immediately reduce total daily insulin to 0.1–0.15 units/kg/day given primarily as basal insulin, with correctional rapid-acting insulin only for glucose exceeding 180 mg/dL. 3
• Continue basal insulin coverage even with minimal intake rather than relying solely on correction doses, to prevent rebound hyperglycemia and ketosis. 3
• For patients who are NPO or have very poor intake, use a basal-plus-correction regimen rather than scheduled prandial insulin. 3
• Never fully discontinue basal insulin in insulin-dependent patients, even when NPO, to prevent diabetic ketoacidosis. 3

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Common Pitfalls to Avoid

• The most dangerous error is maintaining the increased insulin doses beyond 24–48 hours, as this creates severe hypoglycemia risk when steroid effects dissipate. 2
• Do not delay dose reduction when fasting glucose falls below 100 mg/dL or any hypoglycemic episode occurs; failure to adjust promptly is a common management gap. 3, 2
• Avoid using sulfonylureas during this transition period as they increase hypoglycemia risk. 2
• Do not rely solely on correction insulin without adjusting scheduled basal doses; this reactive approach is unsafe. 3

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Expected Clinical Outcomes

• After a 50–60% basal-dose reduction, fasting glucose should stabilize within 80–130 mg/dL in 3–7 days without further hypoglycemic episodes. 3
• If hyperglycemia persists (fasting glucose >180 mg/dL), titrate the basal dose upward by 2 units every 3 days until the fasting target is achieved. 3
• Properly adjusted basal insulin provides consistent 24-hour coverage without causing nocturnal hypoglycemia or early-morning hyperglycemia. 3

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Summary Algorithm

1. At 48 hours post-dexamethasone: Reduce Lantus from 28 units to 16–18 units (50–60% reduction). 2
2. Return carbohydrate ratio from 1:6 to 1:10 (or 1:12 with poor intake). 2
3. Switch to standard correction scale (2 units for glucose >250 mg/dL, 4 units for >350 mg/dL). 3, 2
4. Monitor glucose every 4–6 hours for the next 24–48 hours. 2
5. If glucose <70 mg/dL: treat immediately and reduce insulin by 10–20%. 3, 2
6. If fasting glucose <100 mg/dL: reduce Lantus by an additional 10–20%. 1
7. Continue monitoring for 72 hours total to ensure complete resolution of steroid effect. 2