Should a patient with elevated overnight blood glucose levels on Lantus (insulin glargine) 40 units in the morning and 45 units in the evening, and a clear liquid diet, receive an additional evening dose of Lantus (insulin glargine)?

Should PM Lantus Be Administered?

Yes, administer the PM Lantus dose of 45 units tonight. The patient's elevated overnight blood glucose levels (184/200 mg/dL) indicate inadequate basal insulin coverage, and withholding the evening dose will worsen hyperglycemia and increase risk of complications 1.

Rationale for Continuing PM Lantus on Clear Liquid Diet

Basal insulin addresses fasting and between-meal glucose levels, not meal coverage. The patient's overnight readings of 184-200 mg/dL reflect insufficient basal insulin suppression of hepatic glucose production, which occurs continuously regardless of oral intake 2, 3. Clear liquid diets still provide carbohydrates (typically 50-100g/day from juices, broths, and gelatin), requiring continued basal insulin coverage 4.

Key Physiologic Principles

• Basal insulin controls endogenous glucose production from the liver, which continues 24/7 even during fasting or minimal oral intake 2, 3
• Overnight glucose levels of 184-200 mg/dL indicate the current basal insulin regimen (40 units AM, 45 units PM) is insufficient 2
• Withholding basal insulin leads to uncontrolled hyperglycemia within 12-24 hours, even without food intake 4

Dose Adjustment Considerations

The current PM dose of 45 units should be administered, but may require upward titration. With fasting glucose ≥180 mg/dL, the American Diabetes Association recommends increasing basal insulin by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL 2, 5.

Titration Algorithm for Clear Liquid Diet

• Continue PM Lantus 45 units tonight 2
• If fasting glucose remains ≥180 mg/dL for 3 consecutive days, increase PM dose by 4 units 2, 5
• If fasting glucose is 140-179 mg/dL, increase PM dose by 2 units every 3 days 2
• Target fasting glucose: 80-130 mg/dL 2, 5

When to Reduce Basal Insulin on Clear Liquids

Dose reduction is only indicated for specific high-risk scenarios, which do not apply here. The American Diabetes Association recommends reducing basal insulin by 20-50% only in patients with:

• Poor oral intake AND recurrent hypoglycemia (glucose <70 mg/dL) 2, 4
• Elderly patients (>65 years) with renal failure (eGFR <45 mL/min) 2
• Documented hypoglycemia episodes without clear cause 2

This patient has hyperglycemia (184-200 mg/dL), not hypoglycemia, making dose reduction contraindicated 2, 4.

Critical Pitfalls to Avoid

Never withhold basal insulin based solely on reduced oral intake. This common error leads to:

• Rapid deterioration of glycemic control within 12-24 hours 4
• Increased risk of diabetic ketoacidosis in insulin-dependent patients 4
• Delayed wound healing and increased infection risk in hospitalized patients 4

Sliding scale insulin alone is explicitly condemned by all major diabetes guidelines and should never replace scheduled basal insulin 2, 4. The patient requires both basal insulin coverage (Lantus) and correction doses for hyperglycemia, not correction doses alone 2, 4.

Monitoring Requirements

Check fasting glucose daily during clear liquid diet and adjust PM Lantus every 3 days based on patterns 2, 5:

• If glucose remains >180 mg/dL: increase PM dose by 4 units 2
• If glucose 140-179 mg/dL: increase PM dose by 2 units 2
• If glucose <80 mg/dL on 2+ occasions: decrease PM dose by 10-20% 2

Reassess insulin requirements when transitioning back to regular diet, as total daily insulin needs may increase with full carbohydrate intake 2, 4.