What adjustments should be made to a patient's Lantus (insulin glargine) dose after experiencing hypoglycemia with a fasting blood glucose of 47, 12 hours postprandial, on a current dose of 18 units?

Immediate Lantus Dose Reduction Required for Documented Hypoglycemia

Reduce the Lantus dose from 18 units to 14-16 units immediately (a 10-20% reduction) due to the documented fasting blood glucose of 47 mg/dL, which represents significant hypoglycemia requiring urgent intervention. 1

Critical Context: Why This Hypoglycemia is High-Risk

This fasting glucose of 47 mg/dL is particularly concerning because:

• 84% of patients who develop severe hypoglycemia (<40 mg/dL) had a preceding episode of hypoglycemia (<70 mg/dL) during the same period 1, 2
• 75% of hospitalized patients who experience hypoglycemia do not have their basal insulin adjusted before the next dose, leading to recurrent severe hypoglycemic events 1, 2
• The correction insulin given 12 hours ago should not affect current fasting glucose—this hypoglycemia reflects excessive basal insulin coverage 1

Specific Dose Adjustment Algorithm

Choose Your Reduction Percentage:

Reduce by 20% (to 14 units) if: 1

• Other near-hypoglycemic values (<80 mg/dL) have been documented recently
• Patient has renal insufficiency or acute kidney injury
• Patient has impaired awareness of hypoglycemia
• This represents a particularly severe episode (BG <50 mg/dL, as in this case)

Reduce by 10% (to 16 units) if: 1

• This is the first documented hypoglycemic episode
• No other risk factors are present
• Patient has good hypoglycemia awareness

Given the severity (BG 47 mg/dL), I recommend the 20% reduction to 14 units. 1

Immediate Monitoring Requirements

After dose adjustment: 1

• Check fasting blood glucose daily for at least one week 1
• Target fasting glucose range: 90-150 mg/dL (more conservative than the usual 80-130 mg/dL target given recent hypoglycemia) 1
• Do not resume aggressive titration until stable for 3-5 days without hypoglycemia 1

Root Cause Analysis Required

Investigate these common triggers for nocturnal hypoglycemia: 2, 1

• Nutrition-insulin mismatch: Was dinner skipped or significantly smaller than usual? 2, 1
• Timing issues: Was the Lantus given at an unusual time? Was the correction insulin given too close to bedtime? 2
• Renal function: Check for acute kidney injury or declining renal function, which reduces insulin clearance 1
• Alcohol consumption: Evening alcohol significantly increases hypoglycemia risk 1
• Unexpected interruption of nutrition: Was there emesis, new NPO status, or reduced oral intake? 2

Patient Safety Measures

Implement these immediately: 1

• Document this hypoglycemic episode in the medical record and track for quality improvement 1, 2
• Educate patient on recognizing early hypoglycemia symptoms (tremor, sweating, confusion, palpitations) 1
• Ensure patient always carries fast-acting glucose sources (glucose tablets, juice) 1
• Recommend medical identification indicating diabetes and hypoglycemia risk 1

Common Pitfall to Avoid

Do not continue the same 18-unit dose "just this once" or delay the reduction. Studies show that 75% of patients with documented hypoglycemia receive no dose adjustment before their next insulin administration, leading to recurrent severe hypoglycemia in 84% of cases. 1, 2 The dose must be reduced immediately.

When to Resume Titration

Once fasting glucose values are stable in the 90-150 mg/dL range for at least one week without further hypoglycemia, you may cautiously resume upward titration if needed, increasing by only 2 units every 3 days based on fasting glucose patterns. 3, 1