What is the appropriate Lantus (glargine) dose and insulin regimen for a patient with a hemoglobin A1c (HbA1c) of 13.1%, transitioning off an insulin drip, with a body mass index (BMI) of 38 and impaired renal function (creatinine 0.77), who is new to insulin therapy?

Insulin Regimen for DKA Transition in Insulin-Naïve Patient

Start Lantus at 20-25 units once daily (0.2 units/kg), use a carbohydrate ratio of 1:8 for meal coverage with rapid-acting insulin, and implement a correction scale starting at 2 units for glucose 150-200 mg/dL, increasing by 2 units for each 50 mg/dL increment. 1

Basal Insulin (Lantus) Dosing

For this 103 kg patient with severe hyperglycemia (A1C 13.1%) transitioning from insulin drip:

• Calculate total 24-hour insulin from the drip, then give half as basal Lantus 1

  • If drip data unavailable, start at 0.2 units/kg = approximately 20-21 units once daily 1
  • The creatinine of 0.77 mg/dL indicates preserved renal function (normal for this patient), so no dose reduction needed 2

• Given the markedly elevated A1C (13.1%) and obesity (BMI 38), consider starting at the higher end: 0.2-0.25 units/kg = 20-25 units 1

  • Start with 25 units Lantus once daily at bedtime for this severely hyperglycemic patient 1

• Titrate by 2-4 units (or 10-15%) every 2-3 days based on fasting glucose, targeting fasting glucose 100-130 mg/dL 1, 3

Prandial (Mealtime) Insulin Coverage

This patient requires basal-bolus therapy given the severe hyperglycemia and DKA presentation:

• Start rapid-acting insulin (lispro, aspart, or glulisine) at 4 units per meal or 10% of basal dose per meal = approximately 2-3 units 1

  • Given the A1C >10%, start with 4-5 units before each meal 1

• Carbohydrate ratio: 1:8 (1 unit per 8 grams of carbohydrate) 4, 2

  • This aggressive ratio is appropriate for severe hyperglycemia and obesity 4
  • If postprandial glucose exceeds 250 mg/dL, tighten to 1:6 ratio 4, 2

Correction Scale (Sliding Scale)

Use the following correction insulin scale with rapid-acting insulin before meals and at bedtime:

Blood Glucose	Additional Units
150-200 mg/dL	2 units
201-250 mg/dL	4 units
251-300 mg/dL	6 units
301-350 mg/dL	8 units
>350 mg/dL	10 units and notify provider

4, 2

• This uses the "1800 rule" with correction factor of approximately 1 unit per 25 mg/dL above 150 mg/dL 4

Complete Initial Regimen Summary

For this 103 kg patient:

• Lantus: 25 units once daily at bedtime 1
• Rapid-acting insulin: 4-5 units before each meal 1
• Carbohydrate coverage: Add 1 unit per 8 grams of carbohydrate 4, 2
• Correction scale: As outlined above, administered with mealtime insulin 4, 2
• Add metformin if not contraindicated (renal function is adequate) 1

Monitoring and Titration Protocol

• Check blood glucose before each meal and at bedtime (minimum 4 times daily) 4, 2
• Target glucose: 100-180 mg/dL 4
• Increase Lantus by 2-4 units every 2-3 days if fasting glucose remains >130 mg/dL 1, 3
• Adjust mealtime insulin by 1-2 units if postprandial glucose consistently >180 mg/dL 1

Critical Pitfalls to Avoid

• Do not delay prandial insulin initiation - with A1C 13.1%, basal insulin alone will be insufficient 1
• Avoid overbasalization - if bedtime-to-morning glucose differential exceeds 50 mg/dL, increase prandial rather than basal insulin 1
• If hypoglycemia occurs (<70 mg/dL), reduce the corresponding insulin dose by 10-20% immediately 4, 2
• Ensure patient education on hypoglycemia recognition and treatment before discharge 1
• The progressive nature of diabetes means this regimen will require ongoing adjustment - schedule follow-up within 1-2 weeks 1