What should be the Lantus (insulin glargine) dose, carb ratio, and correction scale for a 62-year-old female with type 2 diabetes, BMI 28, and poor oral intake, 24 hours after receiving 10mg of dexamethasone (Dex) and 8mg this morning, currently on 8 units of Lantus at home and 12 units tid with meals?

Insulin Management for Dexamethasone-Induced Hyperglycemia with Poor Oral Intake

For this patient receiving high-dose dexamethasone with poor oral intake, increase Lantus to 20-25 units once daily (approximately 0.3-0.4 units/kg), hold all prandial insulin until oral intake improves, and implement a correction scale using rapid-acting insulin every 6 hours with a correction factor of 1 unit per 30-40 mg/dL above 180 mg/dL.

Rationale for Basal Insulin Adjustment

The dexamethasone doses (10 mg yesterday, 8 mg this morning) create severe insulin resistance requiring aggressive basal insulin adjustment. For patients receiving high-dose glucocorticoids with two blood glucose readings >250 mg/dL, guidelines recommend initiating insulin at 1.0-1.2 units/kg per day, distributed as 25% basal and 75% prandial 1. However, this patient's poor oral intake fundamentally changes the approach.

Calculating the Appropriate Dose

• Her current home regimen totals 44 units daily (8 units Lantus + 36 units prandial), which equals approximately 0.68 units/kg/day for a 65 kg patient 1
• With dexamethasone-induced hyperglycemia, insulin requirements typically increase by 0.3-0.4 units/kg/day 1
• For hospitalized patients with poor oral intake and glucocorticoid use, start with reduced total daily dose of 0.1-0.15 units/kg/day given mainly as basal insulin 1
• However, given her existing insulin use and high-dose dexamethasone, a middle-ground approach of 0.3-0.4 units/kg basal insulin (20-26 units) is appropriate 1

Managing Poor Oral Intake

The critical pitfall here is continuing scheduled prandial insulin with poor oral intake, which creates severe hypoglycemia risk 1.

• Withhold all scheduled prandial insulin when oral intake is poor 1
• Provide basal insulin coverage only, as this represents 30-50% of total daily insulin requirements 2
• Use correction doses of rapid-acting insulin before meals or every 6 hours only if the patient actually eats 1

Correction Scale (Sliding Scale)

For correction insulin with poor oral intake and dexamethasone use:

• Blood glucose 180-220 mg/dL: 2 units rapid-acting insulin 1
• Blood glucose 221-260 mg/dL: 4 units rapid-acting insulin 1
• Blood glucose 261-300 mg/dL: 6 units rapid-acting insulin 1
• Blood glucose >300 mg/dL: 8 units rapid-acting insulin and notify physician 1

This represents a "more resistant sliding scale" appropriate for dexamethasone-induced hyperglycemia 1.

Carbohydrate Ratio - Currently Not Applicable

Do not use carbohydrate counting or fixed prandial doses until oral intake improves 1. The patient should receive correction insulin only, administered:

• Before meals if eating (assess meal tray first) 1
• Every 6 hours if NPO or minimal intake 1

Once oral intake normalizes, restart prandial insulin at 4 units per meal or 10% of basal dose (approximately 2 units per meal initially) 2, 3.

Dexamethasone-Specific Considerations

Dexamethasone creates a unique glycemic pattern:

• Peak hyperglycemia occurs in afternoon and evening, 6-12 hours post-dose 1, 4
• A triphasic pattern may emerge: constant hyperglycemia, transient improvement, then another hyperglycemic plateau 4
• Insulin requirements can decline rapidly after dexamethasone is stopped; reduce insulin doses by 20-30% immediately when steroids are discontinued 1

For ongoing dexamethasone therapy, consider adding NPH insulin 0.1-0.3 units/kg (6-20 units) in the morning to specifically target afternoon/evening hyperglycemia 1.

Monitoring Requirements

• Check blood glucose every 6 hours minimum, or before meals if eating 1
• Reassess insulin doses daily while on dexamethasone 1
• Target blood glucose 140-180 mg/dL in hospitalized patients (more permissive given poor oral intake and hypoglycemia risk) 1
• If blood glucose consistently <100 mg/dL, reduce basal insulin by 20% 1, 2

Critical Safety Points

• The combination of dexamethasone, poor oral intake, and insulin creates bidirectional risk: hyperglycemia from steroids versus hypoglycemia from inadequate nutrition 1
• Never give scheduled prandial insulin to patients not eating 1
• Dexamethasone increases insulin resistance by decreasing glucose oxidation and cellular uptake independently of blood flow 5
• When dexamethasone is discontinued, immediately reduce all insulin doses by 20-30% to prevent severe hypoglycemia 1