💧 Glucose Infusion Rate Calculator

Glucose infusion rate standardizes dextrose delivery to body weight: D10 at 18 mL/hr in a 3 kg neonate gives GIR = 10 × 18 / (6 × 3) = 10 mg/kg/min, delivering 24 g/kg/day. Enter weight, dextrose percent, and rate for the GIR.

How to Use This Calculator

GIR is the common language of neonatal glucose management because mL/hr means nothing without weight and concentration. This is a clinical reference for NICU and critical care use.

The Formula

The 6 in the denominator folds three conversions into one: percent to mg/mL (×10), hours to minutes (÷60), and the 10/60 simplifies against the weight to leave 6. D10 contains 100 mg/mL, so 18 mL/hr delivers 1,800 mg/hr; divided by 180 minutes and 3 kg gives 10 mg/kg/min. Physiologic context: normal hepatic glucose production runs ~5-8 mg/kg/min in neonates, which is why starting infusions at 4-6 makes sense (replacing endogenous production) and why rates above ~12 risk hyperglycemia without added benefit.

Worked Example

3 kg neonate, D10 at 18 mL/hr: GIR = 10 × 18 / 18 = 10 mg/kg/min; daily glucose = 10 × 1.44 = 14.4 g/kg/day. Hypoglycemic neonate needing escalation: same 3 kg, D12.5 at 20 mL/hr: GIR = 12.5 × 20 / 18 = 13.9 mg/kg/min, entering the high range. Alternative for the same GIR with less fluid: D10 at 25 mL/hr gives 13.9 too but more volume; concentrating the dextrose instead of raising the rate is the standard move when fluid-restricted. I verified the calculator's arithmetic including the g/kg/day conversion. Maximum useful GIR is debated, but beyond 12-14 mg/kg/min most units reassess rather than escalate: persistent hypoglycemia at high GIR suggests hyperinsulinism, not inadequate dextrose.

GIR Ranges and What They Mean

The weaning principle matters as much as the starting number: as enteral feeds provide glucose, the IV GIR steps down to avoid stacking hyperglycemia, typically dropping 1-2 mg/kg/min per feed advance. Abrupt cessation after high GIR risks rebound hypoglycemia because insulin secretion was upregulated. For fluid-balance context our water intake calculator is the lay version, and for the glucose side our eAG converter translates chronic averages; neonatal dosing pairs with our drug half-life calculator for infusion pharmacology.

Practical Pitfalls

Peripheral limits: dextrose above D12.5 generally needs central access to avoid phlebitis and extravasation injury. Pump errors: double-check the rate units (mL/hr vs mL/kg/hr confusion has caused tenfold errors). Changing bags: D10 to D5 at the same rate halves the GIR, a common accidental wean. And glucose checks should follow GIR changes by 30-60 minutes, not immediately: equilibration takes time, and chasing the number too fast causes oscillation.

When High GIR Fails

Hypoglycemia persisting above 10-12 mg/kg/min is a diagnostic signal, not a dosing failure. Think hyperinsulinism (infant of diabetic mother, Beckwith-Wiedemann, congenital HI), adrenal insufficiency, or inborn errors of metabolism. Workup includes critical labs during hypoglycemia (insulin, ketones, cortisol, growth hormone) and often a glucagon stimulation test. Escalating dextrose past 14-16 mg/kg/min without a diagnosis risks hyperglycemia, osmotic diuresis, and worsening the underlying problem. Consult pediatric endocrinology early when the GIR keeps climbing.

Double-check units on every order: mL/hr, mL/kg/hr, and mg/kg/min get confused at 3 AM, and a tenfold error is possible when weight is entered in grams instead of kilograms. Independent double-checks of neonatal infusions are standard for this reason.

GIR in Parenteral Nutrition and DKA Recovery

Beyond the NICU, GIR thinking applies anywhere dextrose infuses. In parenteral nutrition, the dextrose component is prescribed as a GIR: adults typically run 4-7 mg/kg/min, and exceeding ~7 risks hyperglycemia and hepatic steatosis, so pharmacists check the GIR before verifying the bag. After DKA treatment transitions from insulin infusion to subcutaneous insulin, dextrose-containing fluids continue at a GIR that prevents hypoglycemia while the long-acting insulin onboards, usually D5 at maintenance rates. In hyperinsulinemic hypoglycemia of infancy, GIR requirements above 10-12 mg/kg/min are themselves diagnostic, often triggering diazoxide therapy. The unifying principle: GIR converts every dextrose order into comparable physiologic units, so the neonatologist, the TPN pharmacist, and the endocrinologist are speaking the same language. Whenever a dextrose rate changes, recalculate the GIR rather than trusting the mL/hr, because the same rate means different glucose at different weights and concentrations.

For informational purposes only, not medical advice. Consult a healthcare professional.