In a patient with severe hyperglycemia (blood glucose ~600 mg/dL) who is taking metformin 1000 mg twice daily, insulin glargine (Lantus) 18 units at bedtime, and low‑dose correctional (sliding‑scale) insulin, should the correctional insulin be changed to a high‑dose scale or should another adjustment to the insulin regimen be made?

Increase the Basal Insulin (Lantus) Dose Substantially – Do Not Simply Switch to High-Dose Correctional Insulin

With a blood glucose of 599 mg/dL on 18 units of Lantus, the patient's basal insulin dose is grossly inadequate and must be increased aggressively; simply escalating to a high-dose correctional scale will not address the underlying problem and is associated with worse glycemic control. 1, 2

Why Correctional Insulin Alone Fails

Current guidelines explicitly condemn relying on sliding-scale (correctional) insulin alone for patients with established diabetes 1, 2. The evidence is clear:

• Correctional insulin only treats hyperglycemia after it occurs – it does not prevent it 1
• Studies show sliding-scale insulin alone is associated with 3-fold higher risk of hyperglycemic episodes compared to scheduled insulin regimens 3
• The 2022 Endocrine Society guidelines state that for patients with confirmed admission glucose ≥180 mg/dL, scheduled insulin therapy should be initiated 2
• Even switching to a "high-dose" correctional scale perpetuates this reactive (rather than proactive) approach

The Correct Approach: Aggressive Basal Insulin Titration

Your patient needs a substantial increase in basal insulin with the following strategy:

Immediate Basal Insulin Adjustment

1. Calculate total daily insulin needs: For a patient with severe hyperglycemia (BG ~600 mg/dL), estimate 0.3-0.5 units/kg/day as total daily dose 1

   • If patient weighs 80 kg: 24-40 units total daily dose
   • Allocate 50% to basal insulin = 12-20 units minimum (he's currently on only 18 units)

2. More aggressive approach given severity: With BG of 599 mg/dL, consider:

   • Increase Lantus by 20-30% immediately (from 18 to 22-24 units) 4
   • Alternatively, increase by 4-6 units as an initial step
   • Titrate every 2-3 days by 2-4 units until fasting glucose reaches 100-140 mg/dL 1, 2

Add Scheduled Prandial Insulin

Since the patient has persistent severe hyperglycemia (≥2 readings ≥180 mg/dL), guidelines recommend adding scheduled prandial insulin rather than just increasing correctional doses 2:

• Add rapid-acting insulin before meals: 4-6 units per meal initially
• This creates a basal-bolus regimen, which consistently outperforms correctional insulin alone 1, 5
• Continue low-dose correctional insulin for fine-tuning

Continue Metformin

• Keep metformin 1000 mg BID unless contraindicated (renal dysfunction, acute illness) 4
• Metformin provides important non-glycemic benefits and can be used safely in most hospitalized patients 6

Key Pitfalls to Avoid

⚠️ Do not simply escalate to high-dose correctional insulin – this perpetuates the failed reactive approach and increases risk of both hyperglycemia and hypoglycemia 1, 3

⚠️ Do not undertitrate basal insulin – 18 units is clearly insufficient for this patient's needs given the severe hyperglycemia

⚠️ Do not delay intensification – with glucose of 599 mg/dL, aggressive intervention is needed immediately to prevent complications 2

Monitoring Plan

• Check fasting glucose daily to guide basal insulin titration
• Check pre-meal glucose to guide prandial insulin dosing
• Target glucose range: 100-180 mg/dL 1, 2
• Adjust basal insulin every 2-3 days until fasting glucose is controlled 1

The evidence strongly supports that scheduled insulin therapy (basal-bolus) is superior to correctional insulin alone for achieving glycemic control while minimizing complications 1, 2, 5, 3. Your patient needs more basal insulin coverage, not just more reactive correctional dosing.