Safety of Administering 15 Units of Lantus with Blood Glucose of 81 mg/dL
Administering 15 units of Lantus (insulin glargine) at bedtime with a blood glucose of 81 mg/dL is not recommended due to the high risk of nocturnal hypoglycemia.
Risk Assessment
A blood glucose level of 81 mg/dL is already at the lower end of the normal range, and administering a long-acting insulin like Lantus could cause dangerous nocturnal hypoglycemia. Guidelines recommend:
- For patients on basal insulin therapy, blood glucose targets before bedtime should be above 100 mg/dL to minimize the risk of nocturnal hypoglycemia 1
- Lantus (insulin glargine) has a relatively constant basal level of circulating insulin with no pronounced peak, but still carries hypoglycemia risk 2
Recommended Approach
Immediate Action
- Do not administer the full 15 units of Lantus with a blood glucose of 81 mg/dL
- Consider one of these safer alternatives:
- Reduce the Lantus dose by at least 20-30% (to approximately 10-12 units)
- Consume a small bedtime snack containing carbohydrates before administering Lantus
- Delay the insulin administration until blood glucose rises above 100 mg/dL
Monitoring
- Check blood glucose again in 1-2 hours after administration
- Set an alarm to check blood glucose during the night (around 2-3 AM) to detect potential nocturnal hypoglycemia
- Monitor fasting blood glucose the next morning
Adjusting Insulin Regimen
For ongoing management, the insulin regimen should be adjusted based on patterns of blood glucose readings:
- If 50% of fasting blood glucose values are over target: Increase dose by 2 units 3
- If more than 2 fasting blood glucose values per week are <80 mg/dL: Decrease dose by 2 units 3
- Starting doses of basal insulin should be estimated based on body weight (0.1–0.2 units/kg/day) and degree of hyperglycemia 3
Special Considerations
Risk of Overbasalization
- Clinical signals of overbasalization include basal dose greater than 0.5 units/kg, high bedtime-morning glucose differential, hypoglycemia, and high variability 3
- Evidence of overbasalization should prompt reevaluation of the glucose-lowering treatment plan 3
Hypoglycemia Management
If hypoglycemia occurs:
- For confirmed hypoglycemia, administer 15-20g of fast-acting carbohydrate
- Recheck blood glucose after 15 minutes
- If blood glucose remains <100 mg/dL, repeat treatment 1
- For severe cases with altered consciousness, administer IV glucose or glucagon
Conclusion
The immediate safety concern with a blood glucose of 81 mg/dL and administering 15 units of Lantus is the high risk of nocturnal hypoglycemia, which can lead to serious adverse events including severe hypoglycemia. Reducing the dose or ensuring adequate carbohydrate intake before bedtime is essential to prevent this potentially dangerous situation.