What IV fluid is used as the diluent for the insulin infusion?

• A. 0.9% normal saline
• B. 5% dextrose in water
• C. Lactated Ringer's
• D. Half-normal saline

Answer: (A)

Insulin infusions are prepared in a fluid that won’t add glucose, so we can titrate the dose accurately based on frequent glucose monitoring. Using a glucose-free, isotonic diluent keeps the insulin’s effect clear and maintains stable intravascular volume. 0.9% normal saline fits this requirement perfectly: it is isotonic and does not introduce additional sugars, allowing precise insulin titration and straightforward glucose tracking. Using a dextrose-containing fluid would adulterate glucose measurements and make dose adjustments more difficult, and fluids like lactated Ringer’s or half-normal saline bring electrolyte or tonicity changes that aren’t ideal for an insulin drip. So, the best choice for the diluent is normal saline.