Dextrose is glucose. FDA's own regulation puts it plainly: "Corn sugar..., commonly called D-glucose or dextrose, is the chemical alpha-D-glucopyranose," produced "by the complete hydrolysis of corn starch." It is affirmed GRAS under 21 CFR 184.1857 with no limit beyond good manufacturing practice, and it counts as added sugar — FDA names it explicitly in its consumer explainer, which lists added sugars as including "sugars that are added during the processing of foods (such as sucrose or dextrose)."
Two numbers make dextrose interesting. It is less sweet than table sugar — published figures put it in the range of roughly two-thirds to 80 percent of sucrose's sweetness, and the exact figure moves with concentration and temperature, so treat "about 70 percent" as a ballpark rather than a constant. But its glycemic index is the highest possible, because dextrose is the yardstick: as NIH's MedlinePlus puts it, "Pure glucose has the highest GI and is given a value of 100." Everything else on the glycemic index is measured against it. Less sweetness per gram, maximum glucose response per gram.
Why manufacturers use it. Sweetness is often not the point. Dextrose is a reducing sugar and sucrose is not — a 2025 review in Foods notes that "sucrose is not classified as a reducing sugar and therefore does not participate directly in the Maillard reaction," and that adding glucose is "a more effective formulation strategy" when you want browning. That makes dextrose the go-to for crust color and caramel notes in baked and toasted products. It also holds moisture, controls crystallization, lowers freezing point in frozen treats, and has a negative heat of solution, giving that faint cooling sensation on the tongue. Which is why dextrose turns up in plenty of foods no one would call sweet.
How to spot it on a label: "dextrose," "dextrose monohydrate," "corn sugar," or "glucose." Check savory products too — crackers, seasoned chips, deli meats, breads, and taco seasonings often carry it for browning or bulk rather than taste. Its real significance for parents is ingredient-splitting: a product listing dextrose and cane sugar and juice concentrate separately keeps any single sweetener out of the first slot while the Added Sugars line tells the truth. Read the number, not the order.