The glucose drink for pregnancy is a sweet beverage containing a measured dose of sugar, used to screen for gestational diabetes. You’ll typically drink it at your prenatal appointment between 24 and 28 weeks, and your blood is drawn afterward to see how efficiently your body processes that sugar. The drink itself is a medical product (often called Glucola) that contains 50 grams of glucose monohydrate dissolved in water with flavoring.
Why the Test Happens at 24 to 28 Weeks
During pregnancy, your placenta releases hormones, including growth hormone, progesterone, and cortisol, that gradually make your cells less responsive to insulin. This is actually by design: your body resists its own insulin so that more glucose stays in your bloodstream and crosses the placenta to fuel your baby’s growth. In most pregnancies, your pancreas compensates by producing extra insulin and blood sugar stays in a healthy range.
But in roughly 2 to 10 percent of pregnancies, the pancreas can’t keep up, and blood sugar climbs too high. This is gestational diabetes. The reason the test is scheduled between 24 and 28 weeks is that insulin resistance peaks around this time, making it the ideal window to catch the problem. Research shows a direct correlation between maternal blood sugar levels around 28 weeks and the risk of the baby growing too large. For women with higher risk factors, such as obesity or a history of gestational diabetes, some providers screen earlier, around 16 to 18 weeks.
What the Drink Tastes Like and How It Works
The glucose drink is a small bottle of thick, syrupy liquid, usually in flavors like orange, lemon-lime, or fruit punch. It contains a precise 50 grams of glucose monohydrate, essentially pure sugar dissolved in water. Most people compare it to flat soda that’s far too sweet. You’ll be asked to finish it within about five minutes.
The point of the drink is to flood your system with a known quantity of sugar so your blood can be tested under standardized conditions. Eating a candy bar or drinking juice wouldn’t deliver the same controlled dose, which is why a medical-grade product is used. That said, some research has explored food-based equivalents. A study published in Diabetes Care found that 10 strawberry-flavored Twizzlers or 8 Jolly Ranchers delivered a similar 50-gram sugar load and produced no significant difference in blood glucose response compared to the standard drink. Some providers may allow alternatives, but this varies by practice.
The One-Hour Screening Test
The initial screening, sometimes called the one-hour glucose challenge test, does not require fasting. Here’s what to expect:
- Baseline blood draw: A sample is taken to measure your starting blood sugar.
- Drink the glucose solution: You finish the 50-gram drink within the time your provider specifies.
- Wait one hour: You sit in the office or lab. You can’t eat, drink, or walk around extensively during this time.
- Second blood draw: Your blood sugar is measured again at the one-hour mark.
A result below 140 mg/dL is generally considered normal, and no further testing is needed. A result of 190 mg/dL or higher typically means gestational diabetes is diagnosed right away. If your result falls somewhere between those numbers, you’ll be asked to come back for a longer, more detailed test.
The Three-Hour Diagnostic Test
If your one-hour screen comes back elevated, the follow-up is a three-hour glucose tolerance test. This one does require fasting, usually for 8 to 14 hours beforehand, so most providers schedule it first thing in the morning.
The process is similar but more involved. Your fasting blood sugar is drawn first. Then you drink a stronger glucose solution containing 100 grams of sugar. Your blood is drawn three more times: at one hour, two hours, and three hours after drinking. That means four total blood draws over the course of the morning. If two or more of those readings come back higher than expected, gestational diabetes is diagnosed.
The three-hour test takes a bigger physical toll because of the fasting and the larger sugar dose. Plan to bring something to eat for afterward, and arrange your morning so you can sit comfortably for the full duration.
Common Side Effects
The glucose drink is safe, but it doesn’t always feel pleasant. The most common reactions are nausea, lightheadedness, and sweating. These happen because your body is processing a concentrated sugar load on a relatively empty or normal stomach. Some women feel jittery or develop a headache. For most people, symptoms pass within an hour or two after the test.
If you vomit after drinking the solution, the test typically can’t be completed that day because the full dose didn’t stay in your system. Your provider will reschedule, sometimes offering the drink chilled or suggesting you take small sips of water beforehand to settle your stomach.
Why the Test Matters
Gestational diabetes often produces no noticeable symptoms, which is why universal screening is standard. Left undetected and untreated, elevated blood sugar during pregnancy raises the risk of several complications. For the baby, the biggest concern is macrosomia, where excess glucose crosses the placenta and causes the baby to grow unusually large, sometimes over 10 pounds. This increases the likelihood of birth injuries and cesarean delivery. Babies born to mothers with uncontrolled gestational diabetes are also more likely to have low blood sugar, breathing difficulties, and jaundice after birth.
For the mother, poorly controlled blood sugar increases the chance of preeclampsia (dangerously high blood pressure), excess amniotic fluid, and preterm delivery before 37 weeks. Stillbirth risk also rises when glucose levels remain unmanaged. The encouraging part: when gestational diabetes is caught early and blood sugar is well controlled through diet, exercise, or medication, these complications become significantly less likely. Within 24 to 48 hours of delivery, the placental hormones driving insulin resistance clear your system, and blood sugar typically returns to normal.
Tips for Getting Through the Test
You can’t do much to change your results, and you shouldn’t try to “game” the test by restricting carbs beforehand, since the goal is an accurate picture of how your body handles sugar. But you can make the experience more comfortable. Ask your provider if the drink can be served cold, as many women find it easier to tolerate chilled. Some clinics offer different flavors, so it’s worth asking if options are available.
For the one-hour test, eating a balanced meal with protein and fiber a couple of hours before your appointment can help reduce nausea, since fasting isn’t required. For the three-hour test, eat a normal dinner the night before rather than loading up on carbs or cutting them out entirely. Bring a book, your phone charger, and a snack for after the final blood draw. The wait is boring, but the test itself is straightforward, and it provides one of the most actionable pieces of information in your entire prenatal care.