For a 70-year-old male weighing 128 kg with type 2 diabetes who is stopping tirzepatide (Mounjaro) 15 mg weekly, empagliflozin (Jardiance) 25 mg daily, and metformin 2000 mg daily while hospitalized, what should his initial insulin glargine (Lantus) dose, carbohydrate‑to‑insulin ratio, and correction factor be?

Inpatient Insulin Dosing for Hospitalized Type 2 Diabetes Patient

For this 70-year-old, 128 kg patient stopping all oral/injectable diabetes medications, start with Lantus 26 units once daily in the morning, use a 1:15 carbohydrate-to-insulin ratio for meal coverage, and apply the "insulin-sensitive" correction scale starting at 2 units for glucose 141-180 mg/dL.

Initial Basal Insulin Dose Calculation

Given this patient's age ≥70 years, the Endocrine Society guideline specifically recommends a conservative starting dose of 0.2-0.3 U/kg body weight for elderly patients 1. At 128 kg:

• Lower end (0.2 U/kg): 128 × 0.2 = 25.6 units
• Upper end (0.3 U/kg): 128 × 0.3 = 38.4 units

Start with approximately 26 units of Lantus once daily, which represents the lower end of this range. This conservative approach is critical because:

• Age ≥70 years places him at high risk for hypoglycemia 1
• He's transitioning from highly effective medications (tirzepatide 15 mg provides substantial glucose lowering)
• Hospital settings with variable oral intake increase hypoglycemia risk

The total daily dose should be split 50% basal and 50% nutritional/prandial insulin 1. Therefore, with 26 units basal, plan for approximately 26 units total prandial insulin distributed across three meals.

Dosing Schedule

Administer Lantus in the morning rather than bedtime 2. This timing is safer for elderly patients because:

• Morning dosing allows better monitoring throughout the day
• Reduces nocturnal hypoglycemia risk
• Facilitates dose adjustments based on same-day glucose patterns

Carbohydrate-to-Insulin Ratio

Use a 1:15 ratio (1 unit of rapid-acting insulin per 15 grams of carbohydrate consumed). This translates to:

• If eating a meal with 45g carbohydrates: give 3 units rapid-acting insulin
• If eating a meal with 60g carbohydrates: give 4 units rapid-acting insulin
• If eating a meal with 75g carbohydrates: give 5 units rapid-acting insulin

With 26 units total prandial insulin divided by 3 meals = approximately 8-9 units per meal if eating full meals. However, hold prandial insulin if the patient is NPO or not eating 1.

Correction Scale (Supplemental Insulin)

Apply the "insulin-sensitive" column from the Endocrine Society protocol 1:

Blood Glucose (mg/dL)	Rapid-Acting Insulin Dose
141-180	2 units
181-220	4 units
221-260	6 units
261-300	8 units
301-350	10 units
351-400	12 units
≥400	14 units

The insulin-sensitive column is appropriate because:

• He is elderly (≥70 years) 1
• He is insulin-naive
• Risk factors for hypoglycemia are present

Give correction insulin before each meal (if eating) or every 4-6 hours (if NPO) using rapid-acting insulin analogs (lispro, aspart, or glulisine) 1.

Critical Safety Considerations

Discontinue All Non-Insulin Medications

Stop tirzepatide, empagliflozin (Jardiance), and metformin immediately upon hospitalization 1. The guidelines are unequivocal about this:

• Metformin: contraindicated during acute illness due to lactic acidosis risk, especially with potential renal/hepatic compromise during hospitalization 1, 3
• SGLT2 inhibitors (Jardiance): risk of euglycemic DKA, volume depletion, and contraindicated in acute illness 1
• GLP-1/GIP agonists (Mounjaro): delayed gastric emptying complicates perioperative management and insulin dosing 1

Hypoglycemia Management Protocol

If blood glucose drops below target:

• BG <70 mg/dL: Reduce total daily insulin dose by 10-20% 1
• BG <40 mg/dL: Reduce total daily insulin dose by 20-40% 1
• Treat with 15g fast-acting carbohydrate if patient can swallow safely

Titration Strategy

Adjust basal insulin every 2-3 days based on fasting glucose patterns 4, 5:

• Fasting glucose >150 mg/dL: Increase basal dose by 2 units
• Fasting glucose <80 mg/dL on >2 occasions: Decrease basal dose by 2 units
• Target fasting glucose: 90-150 mg/dL for elderly patients 2, 3

For prandial insulin adjustments:

• Pre-meal glucose consistently >140 mg/dL: Increase previous meal's prandial dose by 10-20% 1
• Pre-meal glucose <70 mg/dL: Decrease previous meal's prandial dose by 10-20% 1

Common Pitfalls to Avoid

1. Never use sliding-scale insulin alone as the sole method of glycemic control—this triples the risk of hyperglycemia and provides inadequate control 1, 6

2. Do not continue oral agents "because the patient was stable at home"—hospitalization creates contraindications that weren't present outpatient 1

3. Avoid aggressive glucose targets in elderly patients—aim for pre-meal glucose 90-150 mg/dL rather than <110 mg/dL to prevent hypoglycemia 2, 3

4. Do not give rapid-acting insulin at bedtime unless the patient is eating a bedtime snack 2, 3

5. Remember to reduce insulin doses by 50% if oral intake is poor rather than holding all insulin 1

Monitoring Requirements

• Check point-of-care blood glucose before each meal and at bedtime (minimum 4 times daily)
• For patients at high risk of hypoglycemia (which includes this patient), consider real-time CGM with confirmatory fingersticks for insulin adjustments if resources available 7
• Monitor for signs of hypoglycemia, especially during the first 48-72 hours of transition

This basal-bolus approach with conservative dosing provides superior glycemic control compared to sliding-scale insulin alone while minimizing hypoglycemia risk in this elderly, insulin-naive patient 1, 6.