The glucose drink used in glucose tolerance tests contains a surprisingly short list of ingredients: dextrose (a simple sugar derived from corn), water, citric acid, sodium benzoate as a preservative, artificial flavoring, and sometimes food dye. That’s essentially it. Most people encounter this drink during pregnancy screening or when being tested for type 2 diabetes, and the recipe is designed to deliver a precise dose of sugar in a form your body absorbs quickly.
The Core Ingredient: Dextrose
The active ingredient is dextrose, which is just another name for glucose, the same sugar your body uses for energy. Commercial dextrose is produced from corn starch through a multi-step process that breaks the starch down into pure glucose molecules. It’s less sweet than table sugar, which is one reason the drink can taste oddly flat or syrupy rather than pleasantly sweet.
The amount of dextrose changes depending on which test you’re taking. A one-hour glucose screening (the most common version during pregnancy) contains 50 grams. If your doctor orders a follow-up or a standalone diagnostic test for type 2 diabetes, that drink contains 75 grams. The three-hour glucose tolerance test used in pregnancy uses 100 grams. For reference, 50 grams of sugar is roughly what you’d find in a 16-ounce bottle of soda, except the glucose drink packs it into a smaller, more concentrated volume.
Preservatives and Acids
Sodium benzoate is the preservative that keeps the drink shelf-stable without refrigeration. It’s the same compound used in soft drinks, fruit juices, and condiments. Citric acid serves double duty: it adds a tart edge to make the drink more palatable and helps maintain the acidity level that keeps sodium benzoate effective. Neither ingredient is present in large amounts, and both are common across the processed food supply.
Flavoring and Food Dyes
The most common version is orange-flavored, which contains artificial orange flavoring along with food dyes, typically FD&C Yellow #6 and Red #40. These are the same synthetic colorants found in candy, sports drinks, and flavored snacks. A lemon-lime version is also available, and it generally skips the food coloring entirely, making it a simpler option if you’re trying to avoid dyes.
The food dyes have drawn some attention in recent years. Red 40, the most widely used synthetic colorant in the U.S. food supply, has been linked in some research to behavioral changes in children and other health concerns at high intake levels. The amount in a single glucose drink is small, but the presence of artificial dyes is one of the main reasons some patients look for alternatives.
What’s Not in It
Despite tasting intensely sweet, the standard glucose drink does not contain high-fructose corn syrup, sucrose (table sugar), or any fat or protein. It’s pure dextrose in water. That’s intentional: the test needs to measure how your body handles a known quantity of glucose specifically, and mixing in other sugars would change how your body metabolizes the dose. The drink is also free of caffeine, gluten, and dairy.
Alternative Glucose Drinks
If the ingredient list bothers you, alternatives do exist. Products like The Fresh Test use non-GMO dextrose sourced from tapioca or corn, flavored with organic lemon and organic mint instead of artificial flavoring and dyes. These alternatives contain no sodium benzoate, no artificial colors, and no synthetic flavoring. They deliver the same 50 grams of dextrose required for the screening test, just in a cleaner package.
Not every provider stocks alternatives, so you may need to purchase one yourself and confirm with your doctor’s office that they’ll accept it before your appointment. The key requirement from a medical standpoint is that the drink delivers the correct dose of glucose in a standardized form. As long as that’s met, most providers are flexible about which brand you use.
Why It Tastes the Way It Does
People often describe the drink as cloyingly sweet, thick, or vaguely like flat orange soda. That reaction makes sense when you consider you’re drinking a concentrated sugar solution with no carbonation, no fat, and no fiber to balance it out. The citric acid helps cut through the sweetness somewhat, but there’s only so much it can do against 50 to 100 grams of pure glucose in a few ounces of liquid. Chilling the drink beforehand and sipping it steadily rather than gulping tends to make it more tolerable. Most clinics will ask you to finish it within five minutes to keep the test timing accurate.