Should glargine (insulin glargine) be held if blood glucose (BG) is less than 100 mg/dL?

Management of Glargine Insulin with Blood Glucose Less Than 100 mg/dL

Glargine insulin should be held if blood glucose is less than 100 mg/dL to prevent hypoglycemia, as administering insulin when blood glucose is already low significantly increases the risk of developing more severe hypoglycemia. 1

Rationale for Holding Glargine When BG < 100 mg/dL

• The American Diabetes Association defines hypoglycemia as any blood glucose level <70 mg/dL (3.9 mmol/L), which represents the initial threshold for counterregulatory hormone release 1
• For hospitalized patients specifically, insulin regimens should be reassessed if blood glucose falls below 100 mg/dL (5.6 mmol/L) to prevent hypoglycemia 1
• Fasting glucose levels <100 mg/dL are predictors of hypoglycemia within the next 24 hours 2
• Severe hypoglycemia can lead to significant morbidity including cognitive impairment, seizures, coma, and in rare cases, mortality 1

Hypoglycemia Risk with Glargine Insulin

• Although insulin glargine provides a relatively constant basal level of circulating insulin with no pronounced peak compared to NPH insulin, it still carries a risk of hypoglycemia 3
• Studies show that insulin glargine has a reduced risk of hypoglycemia compared to NPH insulin, but the risk is not eliminated, especially when blood glucose levels are already low 4
• In clinical trials, severe hypoglycemia and severe nocturnal hypoglycemia were reduced with insulin glargine by 46% and 59% respectively compared to NPH insulin, but still occurred 4

Algorithm for Managing Glargine Insulin When BG < 100 mg/dL

1. Hold the dose: If blood glucose is <100 mg/dL, hold the glargine insulin dose 1
2. Treat hypoglycemia if present: If blood glucose is <70 mg/dL, treat hypoglycemia first before considering any insulin administration 1
3. Reassess insulin regimen: Review the overall insulin regimen and consider dose reduction for subsequent doses 2
4. Adjust basal insulin dose: If fasting blood glucose is consistently <100 mg/dL or if >2 fasting values per week are <80 mg/dL, decrease the glargine dose by 2 units 2
5. Monitor closely: Increase frequency of blood glucose monitoring to ensure recovery and stability 2

Special Considerations

• Patients with a history of hypoglycemia unawareness may require higher glucose thresholds (>100 mg/dL) before insulin administration 1
• Elderly patients and those with renal or hepatic impairment are at higher risk of hypoglycemia and may benefit from more conservative thresholds 1
• For hospitalized patients, a target glucose range of 140–180 mg/dL (7.8–10.0 mmol/L) is recommended for most critically ill and noncritically ill patients, making a threshold of 100 mg/dL appropriate for holding insulin 2

Clinical Pitfalls to Avoid

• Never administer insulin when blood glucose is already in the hypoglycemic range (<70 mg/dL or 3.9 mmol/L) 1
• Avoid relying solely on symptoms to determine if a patient is hypoglycemic; always confirm with blood glucose measurement 1
• Do not discontinue basal insulin completely based on a single low reading; instead, adjust the dose appropriately for subsequent administrations 2
• When simplifying insulin regimens, particularly in older adults, fasting glucose goals of 90–150 mg/dL (5.0–8.3 mmol/L) are appropriate, supporting the practice of holding insulin when glucose is <100 mg/dL 2