The Glucose Infusion Rate (GIR) is a critical metric used primarily in neonatal intensive care units (NICU) and pediatric medicine. It measures the amount of glucose a patient receives per kilogram of body weight per minute (mg/kg/min). Accurate calculation of GIR is essential for maintaining euglycemia (normal blood sugar levels) in neonates, infants, and critically ill patients who are receiving parenteral nutrition or intravenous fluids.
Maintaining an appropriate GIR helps prevent hypoglycemia (low blood sugar), which can cause neurological damage, and hyperglycemia (high blood sugar), which can lead to osmotic diuresis and dehydration. The liver's endogenous glucose production varies by age, so the required GIR must be tailored to the specific developmental stage of the patient.
The GIR Calculation Formula
The standard formula to calculate GIR based on IV rate and dextrose concentration is:
The constant 6 is a simplification factor derived from unit conversions:
Dextrose Concentration (%): Grams per 100 mL.
Conversion: To convert grams/hr to mg/min, we multiply by 1000 (mg/g) and divide by 60 (min/hr).
When you simplify the math: (1000 ÷ 100 ÷ 60) results in the divisor 6.
Calculation Example
Let's look at a practical example for a neonate in the NICU:
Patient Weight: 3.0 kg
IV Fluid: D10W (10% Dextrose)
IV Rate: 12 mL/hr
Using the formula:
Multiply Rate by Concentration: 12 × 10 = 120
Multiply Weight by 6: 3.0 × 6 = 18
Divide the results: 120 ÷ 18 = 6.67 mg/kg/min
Target GIR Ranges
While individual requirements vary based on clinical condition, stress, and medications, general guidelines for initial Glucose Infusion Rates are as follows:
Patient Group
Typical Initial GIR (mg/kg/min)
Target Maintenance Range
Preterm Neonates
4 – 6
4 – 8 (up to 12-14 max)
Term Neonates
3 – 5
4 – 8
Infants / Children
2 – 4
Variable based on needs
Adults
2
2 – 4
Note: This calculator is a support tool. Always verify calculations and clinical decisions with institutional protocols and pharmacy standards.