At what glucose level should I hold Humalog (insulin lispro)?

Threshold for Holding Humalog Insulin Before Meals

Hold Humalog (insulin lispro) when premeal blood glucose is <100 mg/dL (5.6 mmol/L), and always hold if glucose is <70 mg/dL (3.9 mmol/L). 1, 2

Primary Decision Algorithm

Blood Glucose <70 mg/dL (3.9 mmol/L)

• Absolutely hold Humalog - this is the definition of hypoglycemia requiring immediate treatment 1, 2
• Treat hypoglycemia first with 15-20 grams of fast-acting carbohydrate 3
• Do not administer any insulin until blood glucose is confirmed >100 mg/dL 2
• This threshold represents the initial point for counterregulatory hormone release and clinically significant hypoglycemia 1

Blood Glucose 70-100 mg/dL (3.9-5.6 mmol/L)

• Hold the Humalog dose - this range predicts hypoglycemia within the next 24 hours 1, 2
• The American Diabetes Association guidelines specifically state that insulin regimens should be reassessed when blood glucose falls below 100 mg/dL 1, 4
• Allow the patient to eat first, then reassess glucose 1-2 hours postprandially 2
• Consider reducing your Humalog dose for subsequent meals 2

Blood Glucose 100-140 mg/dL (5.6-7.8 mmol/L)

• Give Humalog as prescribed - this is within the safe premeal target range 1
• For non-critically ill patients, premeal glucose targets should be <140 mg/dL 1

Blood Glucose >140 mg/dL (>7.8 mmol/L)

• Give Humalog as prescribed - you are above target and need mealtime insulin coverage 1
• May require correction insulin in addition to your scheduled 4 units if glucose is significantly elevated 1

Critical Safety Considerations for Your Regimen

Why 100 mg/dL is the Appropriate Threshold

• Fasting glucose levels <100 mg/dL are predictors of hypoglycemia within the next 24 hours 1
• The 2023 American Diabetes Association guidelines explicitly recommend reassessing insulin regimens when glucose drops below 100 mg/dL to prevent hypoglycemia 1, 4
• This provides a safety margin above the 70 mg/dL hypoglycemia threshold, especially important with rapid-acting insulin like Humalog 2, 3

Special Concerns with Your Lantus Dose

• Your 44 units of Lantus at bedtime provides basal insulin coverage for 24 hours 2
• If you're experiencing premeal glucose <100 mg/dL, your Lantus dose may need reduction by 2-4 units 2
• The combination of basal insulin (Lantus) plus rapid-acting insulin (Humalog) increases hypoglycemia risk if doses are not properly adjusted 1

When to Modify Your Insulin Regimen

Reduce Lantus Dose If:

• Fasting blood glucose is consistently <100 mg/dL 2
• You have >2 fasting values per week <80 mg/dL 2
• You experience any glucose <70 mg/dL 1, 2
• Decrease Lantus by 2-4 units and monitor closely 2

Reduce Humalog Dose If:

• Premeal glucose is frequently 70-100 mg/dL 2, 4
• You experience hypoglycemia 1-2 hours after meals 2
• Consider reducing from 4 units to 2-3 units per meal 2

Common Pitfalls to Avoid

• Never give Humalog when glucose is <70 mg/dL - this will cause severe hypoglycemia with potential for cognitive impairment, seizures, or loss of consciousness 1, 3
• Don't rely on symptoms alone - always confirm blood glucose with a meter before administering insulin 1, 3
• Don't skip meals after taking Humalog - rapid-acting insulin peaks in 1-2 hours and will cause hypoglycemia without food intake 5
• Don't ignore trends - if you're consistently holding Humalog doses due to low glucose, your overall insulin regimen needs adjustment 2, 4
• Avoid giving Humalog if you're uncertain about eating - if meal intake is questionable, hold the dose and give after eating based on actual carbohydrate consumption 1

Monitoring Recommendations

• Check blood glucose immediately before each meal (before Humalog) 1
• Check fasting glucose each morning (before breakfast, after overnight Lantus) 2
• If glucose is 70-100 mg/dL before a meal, recheck 15-30 minutes after eating to ensure adequate rise 2
• Increase monitoring frequency if you've had any episode of glucose <70 mg/dL 2, 4