Normal Blood Glucose Levels and Insulin Dosing in Brackets
Normal blood glucose levels range from 70-180 mg/dL, with brackets in insulin prescriptions indicating a flexible dosing range that should be adjusted based on actual blood glucose readings.
Normal Blood Glucose Levels
- Target range for most patients: 70-180 mg/dL 1, 2
- Fasting and pre-meal target: 90-150 mg/dL 2
- Post-meal acceptable level: Up to 180 mg/dL 2
The American Diabetes Association recommends maintaining blood glucose between 140-180 mg/dL for hospitalized patients, with more stringent targets (110-140 mg/dL) for select patients if achievable without significant hypoglycemia 1, 2.
Understanding Insulin Dosing in Brackets
When doctors prescribe insulin with doses in brackets (e.g., 5-10 units), this indicates:
- Sliding scale insulin dosing: The actual dose should be selected from within the range based on the current blood glucose reading
- Flexible dosing: Lower doses for lower glucose readings, higher doses for higher readings
- Safety mechanism: Prevents overdosing while allowing for personalized treatment
For example, a prescription might read "Administer insulin 5-10 units if blood glucose is 180-250 mg/dL" - meaning give 5 units at the lower end of the range and up to 10 units at the higher end.
Managing Hyperglycemia (High Blood Sugar)
When Blood Glucose is Too High (>180 mg/dL):
- Initiate insulin therapy when blood glucose ≥180 mg/dL 1, 2
- For critically ill patients: Use intravenous insulin infusion with target range 140-180 mg/dL 1
- For non-critically ill patients: Use subcutaneous insulin with basal, nutritional, and correction components 1
- Monitor frequently: Every 30 minutes to 2 hours during IV insulin therapy 2
Symptoms of Hyperglycemia:
- Osmotic symptoms: Thirst, dry mouth, frequent urination 3
- Neurological symptoms: Dizziness, blurred vision, weakness 3
- Agitation symptoms: Feeling tense, irritability, poor concentration 3
- Malaise symptoms: Headache, nausea 3
Managing Hypoglycemia (Low Blood Sugar)
When Blood Glucose is Too Low (<70 mg/dL):
- Immediate action required: Stop insulin infusion 1
- For conscious patients: Administer 15-20g of rapid-acting carbohydrates 2, 4
- For unconscious patients: Administer IV glucose (D50W 25-50 mL) or glucagon 2
- Recheck blood glucose: After 15 minutes; repeat treatment if still <70 mg/dL 2
- For neurological patients: Treat if <100 mg/dL to avoid neurological complications 1
Symptoms of Hypoglycemia:
- Neurogenic symptoms: Sweating, trembling, hunger, anxiety
- Neuroglycopenic symptoms: Confusion, drowsiness, speech difficulty, seizures
- Severe hypoglycemia (≤40 mg/dL) is independently associated with increased mortality 2
Practical Application of Insulin Dosing in Brackets
- Check current blood glucose level
- Select appropriate dose from the prescribed range:
- Lower end of range for blood glucose closer to target
- Higher end of range for blood glucose further from target
- Document the blood glucose reading and insulin dose administered
- Monitor response and adjust subsequent doses accordingly
Important Considerations
- Avoid rapid fluctuations in blood glucose levels, as glycemic variability is associated with poor outcomes 5
- More frequent monitoring is needed during illness, stress, or changes in medication/diet
- Individualize targets for special populations (elderly, pregnant women, those with comorbidities)
- Document episodes of hypoglycemia in the medical record and track them 1
- Adjust insulin regimen after hypoglycemic episodes to prevent recurrence 2, 4
By understanding normal blood glucose ranges and the meaning of bracketed insulin dosing instructions, patients can better manage their diabetes and prevent complications associated with both hyperglycemia and hypoglycemia.