Calculate glucose infusion rate from dextrose concentration, IV rate, and weight. Includes neonatal/pediatric/adult targets, reverse calculation, dextrose concentration table, and hypoglycemia prot...
The Glucose Infusion Rate (GIR) Calculator determines the rate of glucose delivery in mg/kg/min from IV dextrose infusions. GIR is the standard metric for managing glucose homeostasis in neonatal and critical care settings, where precise glucose delivery prevents both hypoglycemia (seizures, brain injury) and hyperglycemia (osmotic diuresis, increased infection risk, IVH in preterm infants).
Neonates are particularly vulnerable to hypoglycemia due to limited glycogen stores, high metabolic rate, and immature gluconeogenesis. Term neonates typically require a GIR of 4–6 mg/kg/min for maintenance, while preterm infants may need 5–12 mg/kg/min. The calculator supports all standard dextrose concentrations (D5W through D50W), multiple rate units, and patient weight in kg, lbs, or grams.
Beyond simple GIR calculation, this tool provides reverse calculation (what infusion rate is needed to achieve a target GIR), dextrose concentration comparison table, IV access guidance (peripheral vs. central line based on osmolarity), and a neonatal hypoglycemia management protocol. It handles unit conversions between mg/kg/min, mg/kg/hr, g/kg/day, and estimated caloric delivery from dextrose.
Accurate GIR calculation prevents both hypoglycemia (neurological damage) and hyperglycemia (osmotic complications). It is essential for NICU care, TPN management, and critical care glucose optimization. Manual GIR calculations are error-prone — standardized calculation reduces medication errors. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
GIR (mg/kg/min) = (Dextrose% × Rate [mL/hr]) / (Weight [kg] × 6) Alternative formula: GIR = (Dextrose concentration [g/L] × Rate [mL/hr]) / (Weight [kg] × 60) Unit conversions: • mg/kg/hr = GIR × 60 • g/kg/day = GIR × 60 × 24 / 1000 • kcal/day from dextrose = g/day × 3.4 Reverse: Rate (mL/hr) = (Target GIR × Weight [kg] × 6) / Dextrose%
Result: GIR = 5.71 mg/kg/min — within neonatal maintenance range (4–8).
GIR = (10 × 12) / (3.5 × 6) = 120 / 21 = 5.71 mg/kg/min. This is adequate for maintenance glucose delivery in a term neonate. The neonate receives approximately 0.49 g/kg/day of glucose (585 kcal/day from dextrose). If the neonate develops hypoglycemia, increase rate to ~16.8 mL/hr for a GIR of 8 mg/kg/min, or switch to D12.5W at the current rate for a GIR of ~7.1 mg/kg/min.
In total parenteral nutrition (TPN), GIR is a key parameter alongside protein (amino acids) and lipid infusion rates. Standard TPN glucose advancement: start at GIR 4–6 mg/kg/min, advance by 1–2 mg/kg/min daily to a maximum of 10–12 mg/kg/min (neonates) or 4–5 mg/kg/min (adults). Higher glucose infusion rates increase CO₂ production (respiratory quotient >1.0), which can worsen respiratory failure. In critically ill adults, a GIR above 4–5 mg/kg/min is associated with hepatic steatosis, hyperglycemia, and increased infection risk.
At-risk neonates (SGA, LGA, infant of diabetic mother, preterm, perinatal stress): check blood glucose within 1 hour of birth, then every 2–3 hours for the first 24 hours. If glucose <45 mg/dL: oral feed if asymptomatic, IV bolus + infusion if symptomatic or unable to feed. Target: maintain glucose >45 mg/dL (some guidelines use >50 or >60 mg/dL). Serial monitoring every 30 minutes after intervention until stable (>45 on two consecutive checks). Weaning: decrease GIR by 1–2 mg/kg/min every 6–12 hours once glucose is stable, monitoring at each step.
Most neonatal hypoglycemia is transitional (resolves within 48–72 hours as endogenous glucose production matures). Persistent hypoglycemia (>72 hours or requiring GIR >12) warrants investigation for hyperinsulinism, cortisol deficiency, growth hormone deficiency, or inborn errors of metabolism. The critical sample (drawn during a confirmed hypoglycemic episode <40 mg/dL) is essential: insulin, C-peptide, beta-hydroxybutyrate, free fatty acids, cortisol, growth hormone, lactate, ammonia, and acylcarnitine profile. Failure to obtain this sample during the initial hypoglycemic episode often leads to diagnostic delay.
Term neonates: 4–6 mg/kg/min for maintenance. This matches the neonatal hepatic glucose production rate (~4–6 mg/kg/min). Preterm infants have higher needs (5–8 mg/kg/min maintenance, up to 12 mg/kg/min therapeutic). The goal is to maintain blood glucose above 45 mg/dL (some guidelines use 40 or 50 mg/dL). Both hypoglycemia and hyperglycemia are harmful to the neonatal brain. When starting IV dextrose, begin at the lower end of the range and titrate up based on glucose monitoring.
GIR (mg/kg/min) = (Dextrose % × Rate in mL/hr) / (Weight in kg × 6). The factor "6" comes from unit conversions: dextrose % = g/100mL, and dividing mL/hr by 60 gives mL/min. The full derivation: (D g/100mL × Rate mL/hr × 1000 mg/g) / (Wt kg × 1000 g/kg × 60 min/hr) = (D × Rate × 1000) / (Wt × 60000) = (D × Rate) / (Wt × 6). This formula works for any dextrose concentration and any weight.
Two patients receiving the same rate of D10W have very different glucose exposure if one weighs 1 kg and the other 4 kg. GIR normalizes glucose delivery to body weight: 10 mL/hr of D10W in a 1 kg preterm infant = GIR 16.7 mg/kg/min (dangerously high), but in a 4 kg term infant = GIR 4.2 mg/kg/min (maintenance). Without GIR calculation, you might inadvertently cause hyperglycemia in small neonates or hypoglycemia in larger ones.
A GIR requirement >12 mg/kg/min is abnormal and suggests pathological hypoglycemia. Common causes: congenital hyperinsulinism (nesidioblastosis — the most common cause of persistent neonatal hypoglycemia), Beckwith-Wiedemann syndrome, small for gestational age (SGA) with depleted glycogen, inborn errors of metabolism (fatty acid oxidation defects, glycogen storage disease), and cortisol deficiency. If GIR >12 is needed, obtain: insulin/glucose ratio (critical sample during hypoglycemia), cortisol, growth hormone, beta-hydroxybutyrate, free fatty acids, acylcarnitine profile, and pediatric endocrinology consultation.
The maximum dextrose concentration safe for peripheral IV is 12.5% (D12.5W), with an osmolarity of ~631 mOsm/L. Solutions above this threshold are hyperosmolar to the point of causing phlebitis, thrombosis, and if infiltrated, severe tissue necrosis. D15–D70 require central venous access (PICC line, UVC/UAC in neonates, or central line). In emergencies, a D25W or D50W bolus may be given peripherally through a large-bore IV but is not for continuous infusion. Standard practice: if GIR needs exceed what D12.5 can deliver via peripheral IV, place a central line.
Increase dextrose concentration. For example, switching from D10W to D12.5W at the same rate increases GIR by 25%. Common step-ups: D5 → D7.5 → D10 → D12.5 (peripheral max) → D15 → D20 (central required). Conversely, to decrease GIR without changing rate, step down the concentration. Alternatively, you can adjust rate at the same concentration. Most neonatal protocols use rate adjustments first (simpler, no fluid change needed), then concentration increases when rate adjustments alone are insufficient or would cause fluid overload.