At what blood glucose level should I withhold short-acting insulin (regular insulin) to avoid hypoglycemia?

Blood Glucose Thresholds for Holding Short-Acting Insulin

Short-acting insulin should be withheld when blood glucose levels fall below 70 mg/dL (3.9 mmol/L) to prevent hypoglycemia. 1

Understanding Hypoglycemia Risk

Hypoglycemia is a significant concern when administering insulin therapy, particularly short-acting insulin formulations. The American Diabetes Association classifies hypoglycemia into three levels:

• Level 1: Glucose <70 mg/dL but ≥54 mg/dL
• Level 2: Glucose <54 mg/dL
• Level 3: Severe event requiring assistance

The threshold of 70 mg/dL represents the standard level at which counterregulatory hormones begin to be released in response to falling glucose levels 1.

Preventive Approach

Consider reassessing the insulin dosing regimen when glucose falls below 100 mg/dL, as this level can predict potential hypoglycemic events within the next 24 hours 1. This is particularly important in high-risk settings such as:

• Hospitalized patients
• Patients with irregular eating patterns
• Elderly patients (>65 years)
• Patients with renal insufficiency

Patient-Specific Considerations

Blood glucose thresholds for holding short-acting insulin may need adjustment based on:

1. Health status and comorbidities:

   • For healthy individuals with few chronic illnesses: Hold at <70 mg/dL 2
   • For complex/intermediate patients with multiple chronic conditions: Hold at <70 mg/dL but consider higher thresholds 2
   • For very complex/poor health patients: Avoid hypoglycemia entirely with higher thresholds 2

2. Hospital setting considerations:

   • For hospitalized patients, a basal-plus approach is recommended for those fasting or undergoing procedures to avoid hypoglycemia 2
   • The risk of hypoglycemia with basal-bolus insulin is 4-6 times higher than with sliding scale insulin therapy 2

Special Populations

Elderly Patients

For older adults, consider holding short-acting insulin at higher thresholds (80-100 mg/dL) as they have:

• Decreased counterregulatory responses
• Impaired hypoglycemia awareness
• Higher risk of adverse outcomes from hypoglycemia 2

Patients with Type 1 Diabetes

For patients with type 1 diabetes, never completely withhold all insulin, even when holding short-acting insulin:

• Basal insulin must be continued to prevent diabetic ketoacidosis
• Adjust prandial insulin doses based on blood glucose and carbohydrate intake 2

Management After Hypoglycemia

After a hypoglycemic episode requiring holding of short-acting insulin:

1. Administer 15-20g of fast-acting carbohydrates for conscious patients with glucose <70 mg/dL
2. Recheck glucose after 15 minutes
3. Consider dose reduction when restarting insulin therapy
4. Document the hypoglycemic episode and follow up within 1-2 weeks 1

Common Pitfalls to Avoid

• Failing to adjust insulin dose after hypoglycemia: Studies show that 75% of patients do not have their insulin dose changed after a hypoglycemic episode 1
• Ignoring mild hypoglycemia: 84% of patients with severe hypoglycemia had a preceding milder episode 1
• Holding basal insulin in type 1 diabetes: This can lead to diabetic ketoacidosis 2

By adhering to these guidelines and maintaining vigilance around the 70 mg/dL threshold, you can minimize the risk of hypoglycemic events while effectively managing hyperglycemia with short-acting insulin therapy.