What is the recommended Lantus (insulin glargine) dose, carb ratio, and correction scale for a 51-year-old female patient with a history of recurrent diabetic ketoacidosis (DKA) and a current dose of 20 units of Lantus (insulin glargine) daily?

Insulin Dosing for Recurrent DKA Patient

Critical Issue: Recurrent DKA Requires Aggressive Insulin Intensification

This patient's 4th DKA admission this year with only 20 units of Lantus daily indicates severe insulin deficiency and likely non-adherence—she needs immediate transition to a basal-bolus regimen with substantially increased total daily insulin dose to prevent mortality from recurrent DKA. 1, 2

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Recommended Lantus (Basal) Dose

Increase Lantus to 40-50 units daily (approximately 0.5-0.65 units/kg for her 77 kg weight). 1

Rationale:

• Her current 20 units (0.26 units/kg) is grossly inadequate given recurrent DKA 3
• Standard basal insulin dosing for type 1 diabetes ranges from 0.4-0.7 units/kg/day at discharge after DKA 4
• Start conservatively at 40 units and titrate up to 50 units based on fasting glucose monitoring 1
• The most common precipitating cause of recurrent DKA is insulin non-compliance (54.2% of cases), suggesting her actual insulin needs are much higher than her current regimen 3

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Carbohydrate Ratio

Start with 1:10 ratio (1 unit of rapid-acting insulin per 10 grams of carbohydrate) before each meal. 1

Implementation:

• Use rapid-acting insulin analog (lispro, aspart, or glulisine) before each meal 5
• This translates to approximately 5-8 units per typical meal (50-80g carbohydrates) 1
• Adjust ratio every 2-3 days based on 2-hour postprandial glucose readings 1
• If postprandial glucose remains >180 mg/dL, tighten ratio to 1:8; if <100 mg/dL, loosen to 1:12 1

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Correction Scale (Insulin Sensitivity Factor)

Use 1 unit of rapid-acting insulin to lower blood glucose by 50 mg/dL (1:50 correction factor). 1

Correction Dosing Algorithm:

• Target blood glucose: 100-150 mg/dL 1
• For glucose 151-200 mg/dL: add 1 unit
• For glucose 201-250 mg/dL: add 2 units
• For glucose 251-300 mg/dL: add 3 units
• For glucose 301-350 mg/dL: add 4 units
• For glucose >350 mg/dL: add 5 units and check urine ketones immediately 5

Administer correction insulin every 4 hours minimum to avoid insulin stacking. 1

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Complete Daily Insulin Regimen

Total Daily Dose (TDD): Approximately 80-100 units

• Basal (Lantus): 40-50 units once daily (50% of TDD) 1
• Prandial (rapid-acting): 30-50 units total divided across 3 meals (50% of TDD) 1
• Correction doses: as needed per scale above 1

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Critical Pitfalls to Avoid in This High-Risk Patient

1. Inadequate Basal Insulin = Recurrent DKA

• Basal insulin must be given 2-4 hours before any IV insulin is stopped during DKA treatment to prevent rebound ketoacidosis 1, 2, 5
• Never discharge a recurrent DKA patient on basal insulin alone—this is the setup for her current pattern 1

2. Sliding Scale Only = Treatment Failure

• Traditional sliding scale without basal insulin is associated with worse outcomes and higher complication rates 1
• This patient needs structured basal-bolus therapy, not reactive correction-only dosing 1

3. Non-Adherence Assessment is Mandatory

• Recurrent DKA in females is significantly higher than males (p=0.002), suggesting psychosocial barriers 3
• Address barriers to adherence: cost, access, depression, eating disorders, or intentional insulin omission 3
• Structured diabetes education must be provided before discharge (94% of DKA patients should receive this) 3

4. Monitoring Requirements

• Check blood glucose before each meal and at bedtime (minimum 4 times daily) 1
• Check urine or blood ketones if glucose >250 mg/dL 5
• Follow-up within 3-5 days of discharge to adjust doses 1

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Special Considerations for Recurrent DKA

Sick Day Management Education

• Never stop basal insulin, even when not eating 2, 5
• Increase rapid-acting insulin by 10-20% during illness 5
• Check ketones every 4 hours if glucose >250 mg/dL 5
• Seek emergency care if ketones are moderate-to-large despite correction doses 5

Transition from Hospital

• Administer her new basal dose (40 units Lantus) 2-4 hours before stopping IV insulin to prevent immediate DKA recurrence 1, 2, 5
• Ensure she demonstrates proper insulin injection technique before discharge 2
• Provide written sick day rules and emergency contact information 2

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Monitoring and Titration Schedule

Week 1-2 Post-Discharge:

• Increase Lantus by 2-4 units every 3 days if fasting glucose >130 mg/dL 1
• Adjust carb ratios if postprandial glucose consistently >180 mg/dL 1
• Tighten correction factor to 1:40 if corrections are ineffective 1

This aggressive approach is justified by her BMI of 29 (indicating insulin resistance) and her pattern of severe metabolic decompensation. 1, 3