In a 49‑year‑old woman with type 2 diabetes mellitus, hemoglobin A1c 10.9 %, weight 123 kg (BMI ≈ 41 kg/m²), currently on basal insulin glargine (Lantus) 50 U daily, weekly semaglutide (Ozempic) 0.5 mg, and metformin 1000 mg daily, what should her basal insulin dose, insulin‑to‑carbohydrate ratio, and correction factor be?

Insulin Dosing for a 49‑Year‑Old Woman with Severe Uncontrolled Type 2 Diabetes

This patient requires immediate aggressive insulin intensification with both basal and prandial insulin, not just basal titration alone. With an A1c of 10.9%, weight 123 kg, and BMI 41, her current regimen of Lantus 50 units, Ozempic 0.5 mg weekly, and metformin 1000 mg daily is profoundly inadequate and represents therapeutic failure that demands urgent correction.112

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Immediate Basal Insulin Adjustment

Increase Lantus to 70–80 units once daily (approximately 0.57–0.65 units/kg for her 123 kg weight), administered at bedtime.21 This represents an aggressive but necessary escalation given her severe hyperglycemia.2

Basal Insulin Titration Protocol

• If fasting glucose ≥180 mg/dL: increase Lantus by 4 units every 3 days until fasting glucose reaches 80–130 mg/dL.12
• If fasting glucose 140–179 mg/dL: increase by 2 units every 3 days.12
• Critical threshold: When basal insulin approaches 0.5–1.0 units/kg/day (61–123 units), stop further basal escalation and add prandial insulin instead to avoid "over‑basalization" with increased hypoglycemia risk.112

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Initiate Prandial Insulin Coverage Immediately

Start rapid‑acting insulin (lispro, aspart, or glulisure) at 10–12 units before each of the three main meals (breakfast, lunch, dinner).2 With an A1c of 10.9%, this patient clearly needs both basal and prandial coverage from the outset—basal insulin alone will not achieve adequate control.11

Prandial Insulin Titration

• Increase each meal dose by 2 units every 3 days based on 2‑hour post‑meal glucose readings.12
• Target post‑prandial glucose <180 mg/dL.12
• Administer rapid‑acting insulin 0–15 minutes before meals for optimal effect.12

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Carbohydrate‑to‑Insulin Ratio (Carb Ratio)

Start with a 1:10 ratio (1 unit of insulin per 10 grams of carbohydrate).2 This is a reasonable starting point for most adults with type 2 diabetes and severe insulin resistance.2

Calculating the Ratio

• The formula 450 ÷ total daily insulin dose (TDD) can be used to refine the ratio once her insulin doses stabilize.2
• For example, if her eventual TDD is 100 units: 450 ÷ 100 = 4.5, suggesting a ratio of approximately 1:5 (1 unit per 5 grams carbohydrate), which reflects her severe insulin resistance.2
• Adjust the ratio if post‑prandial glucose consistently misses target: tighten the ratio (e.g., from 1:10 to 1:8) if glucose remains >180 mg/dL two hours after meals.2

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Correction Factor (Insulin Sensitivity Factor)

Use a simplified correction scale initially:

• Add 2 units of rapid‑acting insulin for pre‑meal glucose >250 mg/dL.12
• Add 4 units for pre‑meal glucose >350 mg/dL.12

Individualized Correction Factor

• Calculate using the formula: 1500 ÷ TDD (for regular insulin) or 1700 ÷ TDD (for rapid‑acting analogs).2
• For example, if her TDD is 100 units: 1500 ÷ 100 = 15, meaning 1 unit of insulin lowers glucose by approximately 15 mg/dL.2
• Correction dose = (Current glucose – Target glucose) ÷ Insulin Sensitivity Factor.2
• If she has pre‑lunch glucose of 280 mg/dL and target is 130 mg/dL: (280 – 130) ÷ 15 = 10 units correction dose (in addition to her scheduled carbohydrate coverage).2

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Optimize Foundation Therapy

Metformin

Increase metformin to 2000 mg daily (1000 mg twice daily with meals) unless contraindicated.111 Metformin reduces total insulin requirements by 20–30% and provides superior glycemic control when combined with insulin.32 The maximum effective dose is up to 2500 mg/day.1

Ozempic (Semaglutide)

Continue Ozempic 0.5 mg weekly and consider escalating to 1.0 mg weekly after 4 weeks if tolerated.4 The combination of basal insulin plus GLP‑1 receptor agonist provides potent glucose‑lowering with less weight gain and hypoglycemia than intensified insulin regimens alone.11 Semaglutide produces 1.5–1.9% A1c reduction and 5–10% weight loss.4

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Monitoring Requirements

• Check fasting glucose daily to guide basal insulin titration.12
• Check pre‑meal glucose before each meal to calculate correction doses.2
• Obtain 2‑hour post‑prandial glucose after each meal to assess prandial insulin adequacy.12
• Reassess A1c every 3 months during intensive titration.2
• Daily self‑monitoring of blood glucose is essential during the titration phase.11

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Expected Clinical Outcomes

• A1c reduction of 3–4% (from 10.9% to approximately 7–8%) is achievable over 3–6 months with proper basal‑bolus therapy.2
• With appropriately weight‑based basal‑bolus therapy, approximately 68% of patients achieve mean glucose <140 mg/dL, compared with only 38% using inadequate sliding‑scale approaches.2
• Properly implemented basal‑bolus regimens do not increase hypoglycemia incidence when correctly applied.2

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Hypoglycemia Management

• Treat any glucose <70 mg/dL immediately with 15 grams of fast‑acting carbohydrate, recheck in 15 minutes, and repeat if needed.12
• If hypoglycemia occurs without clear cause, reduce the implicated insulin dose by 10–20% immediately.12
• Educate the patient on recognition and treatment of hypoglycemia, including symptoms and the <70 mg/dL threshold.2

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Critical Pitfalls to Avoid

• Do not continue escalating Lantus beyond 0.5–1.0 units/kg/day (61–123 units) without addressing post‑prandial hyperglycemia—this leads to over‑basalization with increased hypoglycemia risk and suboptimal control.112
• Do not delay adding prandial insulin when A1c is 10.9%—this patient clearly needs both basal and prandial coverage from the outset.112
• Do not discontinue metformin when intensifying insulin unless contraindicated—the combination provides superior control with less weight gain.113
• Never use sliding‑scale insulin as monotherapy—correction doses must supplement a scheduled basal‑bolus regimen, not replace it.2
• Do not give rapid‑acting insulin at bedtime as a sole correction dose—this markedly raises nocturnal hypoglycemia risk.12

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Patient Education Essentials

• Insulin injection technique and site rotation to prevent lipohypertrophy.2
• Hypoglycemia recognition and treatment (symptoms, <70 mg/dL threshold, 15‑gram carbohydrate rule).12
• "Sick day" management rules: continue insulin even if not eating, check glucose every 4 hours, maintain hydration.2
• Glucose monitoring: at least four daily measurements (fasting, pre‑meals, bedtime) during titration.12
• Insulin storage and handling requirements.2

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Summary Algorithm

1. Increase Lantus to 70–80 units once daily at bedtime.2
2. Start rapid‑acting insulin 10–12 units before each meal (breakfast, lunch, dinner).2
3. Use 1:10 carb ratio initially (1 unit per 10 grams carbohydrate), adjust based on post‑prandial glucose.2
4. Apply simplified correction scale: +2 units for glucose >250 mg/dL, +4 units for >350 mg/dL.12
5. Increase metformin to 2000 mg daily (1000 mg BID).111
6. Continue Ozempic 0.5 mg weekly, consider escalating to 1.0 mg.4
7. Titrate basal insulin by 4 units every 3 days if fasting glucose ≥180 mg/dL.12
8. Titrate prandial insulin by 2 units every 3 days based on 2‑hour post‑meal glucose.12
9. Monitor daily fasting and pre‑meal glucose, plus 2‑hour post‑prandial readings.12
10. Reassess A1c every 3 months and adjust regimen accordingly.2