Adequate Blood Glucose Levels in Critically Ill Patients
For critically ill patients, the target blood glucose range should be 140-180 mg/dL (7.8-10.0 mmol/L) for the majority of patients. 1, 2
Target Glucose Ranges
Standard Recommendations
- Primary target range: 140-180 mg/dL (7.8-10.0 mmol/L) for most critically ill patients 1
- Insulin therapy should be initiated when blood glucose is ≥180 mg/dL (10.0 mmol/L), checked on two occasions 1
- Hyperglycemia in hospitalized patients is defined as blood glucose levels >140 mg/dL (7.8 mmol/L) 1
Special Populations
More stringent targets (110-140 mg/dL or 6.1-7.8 mmol/L) may be appropriate for:
Less stringent targets may be appropriate for:
- Patients with severe comorbidities: 180-250 mg/dL (10-13.9 mmol/L)
- Settings with limited glucose monitoring capability: 180-250 mg/dL
- Terminally ill patients with short life expectancy: >250 mg/dL (13.9 mmol/L) 1
Evidence Base and Historical Context
The current recommendations are based on key evidence:
The NICE-SUGAR trial demonstrated that intensive glycemic control (80-110 mg/dL) compared to moderate targets (140-180 mg/dL) resulted in:
- No significant treatment advantage
- Slightly higher mortality
- 10-15 fold greater rates of hypoglycemia 1
Multiple meta-analyses support that tight glycemic control increases mortality compared to more moderate targets 1
Even mild hypoglycemia (72-81 mg/dL) is associated with increased mortality in critically ill patients 3
Monitoring and Implementation
Blood Sampling
For patients with invasive vascular monitoring:
- First option: Draw blood from arterial catheter
- Second option: Draw from venous catheter if arterial access unavailable
- Capillary samples should NOT be used 1
For patients without invasive vascular monitoring:
- Capillary samples may be used 1
Analysis Methods
- Blood gas analyzers in the ICU are preferred for arterial/venous samples
- Central laboratory analyzers are acceptable if results are available without delay
- Glucose meters should only be used for capillary samples in less critically ill patients 1
Insulin Administration
- Continuous insulin infusion is the preferred method for critically ill patients 1, 2
- Frequent monitoring (every 30 min to 2 hours) is required during IV insulin therapy 2
Avoiding Complications
Hypoglycemia Prevention
- Severe hypoglycemia (≤40 mg/dL or ≤2.2 mmol/L) and moderate hypoglycemia (41-70 mg/dL or 2.3-3.9 mmol/L) must be avoided 1
- Hypoglycemia is independently associated with increased mortality, with risk increasing with hypoglycemia severity 3
- Report duration, symptoms, glucose administered, and subsequent blood glucose for severe hypoglycemia 1
Glycemic Variability
- High glucose variability is associated with increased mortality, particularly in patients without diabetes 4
- Aim for consistent glucose control within target range 2
Practical Algorithm for Glucose Management
Initial Assessment:
- Check blood glucose on admission to ICU
- Review pre-existing diabetes status and prior glycemic control
Target Selection:
- Standard target (140-180 mg/dL) for most patients
- Consider lower target (110-140 mg/dL) for cardiac/surgical patients if hypoglycemia risk is low
- Consider higher target (180-250 mg/dL) for patients with severe comorbidities or limited monitoring
Insulin Initiation:
- Start insulin therapy when glucose is ≥180 mg/dL on two occasions
- Use continuous IV insulin infusion for critically ill patients
Monitoring:
- Use arterial blood samples analyzed with blood gas analyzer
- Monitor frequently (every 30 min to 2 hours) during insulin infusion
- Report and address any hypoglycemic episodes immediately
By maintaining blood glucose levels within the recommended range of 140-180 mg/dL for most critically ill patients, you can optimize outcomes while minimizing the risks associated with both hyperglycemia and hypoglycemia.