What should the Lantus (insulin glargine) dose, carb coverage, and correction scale be for a 49-year-old male with type 2 diabetes, previously on Metformin (metformin hydrochloride), with a history of Diabetic Ketoacidosis (DKA) and current Hyperglycemia (A1C 12.3%)?

Insulin Dosing for Post-DKA Type 2 Diabetes with Severe Hyperglycemia

Start Lantus at 33 units daily (0.5 units/kg/day), use a carbohydrate ratio of 1:10 for meal coverage with rapid-acting insulin, and apply a correction scale of 1 unit per 30 mg/dL above 150 mg/dL. 1, 2, 3

Basal Insulin (Lantus) Dosing

Begin with 0.5 units/kg/day of insulin glargine (Lantus), which equals approximately 33 units daily for this 66 kg patient. 2, 3 This conservative starting dose is appropriate given:

• Recent DKA resolution requiring careful monitoring 2
• A1C of 12.3% indicating severe hyperglycemia requiring combination basal-bolus therapy 1, 3
• Normal renal function (Cr 0.35) allowing standard dosing 4

The American Diabetes Association recommends that patients presenting with ketoacidosis initially require insulin therapy, with subsequent addition of metformin after metabolic stabilization. 2 Given the DKA has now resolved and the patient is eating well, you should restart metformin (titrating to 2000 mg daily) while continuing insulin therapy. 2

Carbohydrate Coverage (Bolus Insulin)

Use a carbohydrate ratio of 1:10 (1 unit of rapid-acting insulin per 10 grams of carbohydrate) for meal coverage. 1, 3

• Calculate the remaining 50% of total daily insulin dose (approximately 33 units) to be divided among three meals 3
• This translates to roughly 11 units per meal if eating consistently, adjusted based on actual carbohydrate intake 3
• Use rapid-acting insulin (lispro, aspart, or glulisine) given 0-15 minutes before meals 5

Correction Scale

Apply a correction factor of 1 unit per 30 mg/dL above target of 150 mg/dL. 1, 3 This is calculated using the "1800 rule" divided by total daily dose:

• 1800 ÷ 66 units = approximately 27-30 mg/dL per unit 3
• Check blood glucose at least 4 times daily (fasting and before each meal) 1, 3
• Add correction insulin to carbohydrate coverage doses 3

Critical Monitoring and Titration

Titrate basal insulin by 10-30% every 2-3 days based on fasting glucose values, targeting 100-130 mg/dL fasting. 2, 3

• Monitor blood glucose at least 4 times daily during the titration phase 1, 3
• Consider continuous glucose monitoring to prevent DKA recurrence given his history 1
• Recheck A1C in 3 months to assess treatment effectiveness 3

DKA Prevention Education

This patient requires specific sick day management education given his recent DKA. 1, 3

• Never stop insulin during illness, even when not eating 1, 3
• Check urine or blood ketones when glucose exceeds 200 mg/dL, during illness, or when insulin doses are missed 1
• Maintain hydration with non-caloric fluids during illness 1, 3
• Provide supplemental rapid-acting insulin based on blood glucose readings during illness 1
• Watch for Kussmaul respiration (deep, rapid breathing) as a sign of developing acidosis 1

Common Pitfalls to Avoid

• Do not stop metformin abruptly - restart it after DKA resolution and continue during insulin titration, as the combination reduces weight gain and insulin requirements compared to insulin alone 2, 5
• Do not use correction insulin alone without basal coverage - basal-bolus regimens have superior outcomes compared to sliding scale alone in preventing complications 4
• Avoid undertitration - 40% of patients starting insulin remain above A1C 8% due to inadequate dose escalation; be aggressive with titration 6
• Send pancreatic autoantibodies (GAD, IA-2, ZnT8) to confirm this is truly type 2 diabetes and not late-onset type 1, as this affects long-term management 2