The standard dose is one tablet, then recheck your blood sugar after 15 minutes
Most glucose tablets contain 4 to 5 grams of carbohydrate per tablet. One tablet raises blood sugar by roughly 10 to 20 mg/dL in most people, though the exact rise depends on your body weight, how fast your stomach empties, and what else you have eaten recently. The standard first step is to take one tablet, wait 15 minutes, and test again.
If your blood sugar is still below your target range after 15 minutes, take a second tablet. Repeat this cycle—one tablet every 15 minutes—until your blood sugar reaches at least 100 mg/dL or your target range. Most people need between one and three tablets total to bring their blood sugar back to normal, but some need more depending on how low they started and how quickly their body responds.
The 15-minute wait is important. Glucose tablets work fast, but not when ready. Testing sooner than 15 minutes will give you a false low reading and may lead you to take more tablets than you actually need, which can cause your blood sugar to swing too high.
Key Takeaways
- Start with one 4 to 5 gram glucose tablet and wait 15 minutes before rechecking your blood sugar.
- If you are still low after 15 minutes, take another tablet and retest—do not take multiple tablets at once.
- Most people need one to three tablets total to bring blood sugar back to a safe range.
- Testing before 15 minutes have passed will give you an inaccurate reading and may cause you to overtreate.
- Glucose tablets work best on an empty or nearly empty stomach; food in your stomach slows how fast they raise your blood sugar.
Why the 15-minute rule matters
Glucose tablets dissolve quickly and enter your bloodstream within minutes, but the peak effect takes about 15 minutes. If you test at 5 or 10 minutes, your blood sugar may still be climbing and will look lower than it actually is. This leads many people to take a second tablet unnecessarily, which then causes their blood sugar to overshoot into the high range an hour later.
Overshooting creates a cycle: high blood sugar makes you thirsty and tired, then it drops again, and you treat it again. Sticking to the 15-minute retest window breaks that cycle and keeps your corrections smaller and more accurate.
Factors that change how many tablets you need
Your body weight is the biggest factor. A person weighing 120 pounds will see a larger blood sugar rise from one tablet than a person weighing 200 pounds. If you have been taking the same dose for years and it suddenly stops working as well, your weight may have changed, or your insulin sensitivity may have shifted due to stress, illness, or changes in your activity level.
What you have eaten recently also matters. If you took your glucose tablets on a completely empty stomach, they work faster and raise your blood sugar more. If you just finished a meal with fat or protein, the tablets will work more slowly because your stomach is busy digesting other food. In that case, you may need to wait longer than 15 minutes or take an extra tablet.
Some medications, including certain blood pressure drugs and steroids, can make it harder for glucose to raise your blood sugar. If you take any of these and your usual dose stops working, mention it to your doctor or diabetes educator—they may recommend adjusting your dose.
What to do if one tablet is not enough
After 15 minutes, if your blood sugar is still below 100 mg/dL, take a second tablet. Do not take two tablets at once hoping to speed things up—taking them one at a time lets you see how your body responds and prevents you from overshooting. Wait another 15 minutes and test again.
If you regularly need more than two tablets to bring your blood sugar back to normal, talk to your doctor or diabetes educator. You may need to adjust your insulin dose, your meal timing, or your activity level. Repeatedly needing large corrections can signal that something in your routine has shifted.
Glucose tablets versus other fast carbohydrates
Glucose tablets are designed specifically to raise blood sugar quickly and predictably. Other fast carbohydrates—juice, regular soda, hard candy, honey—work too, but they are less reliable. A glass of juice might contain anywhere from 12 to 20 grams of carbohydrate depending on the brand and how full the glass is. Glucose tablets come in a fixed dose, so you always know exactly what you are taking.
Glucose tablets also do not require you to measure or pour anything, which matters when you are shaky or confused from low blood sugar. You can carry them in your pocket, keep them in your car, and use them in any situation without drawing attention or needing a cup. For these reasons, they are the first choice for treating lows, especially when you are away from home.
Storing and checking your tablets
Glucose tablets stay potent for years if kept in a cool, dry place. Heat and humidity break them down, so do not leave them in a hot car or a steamy bathroom. Check the expiration date on the bottle before you use them—expired tablets may not raise your blood sugar as much as fresh ones.
Keep tablets in multiple places: your purse or backpack, your car, your desk at work, and your nightstand. Low blood sugar can happen anywhere, and having tablets within arm's reach means you can treat it when ready instead of searching for them while feeling shaky or confused.
Common mistakes when taking glucose tablets
The most common mistake is taking multiple tablets at once instead of one at a time. This leads to overshooting—your blood sugar climbs too high, you feel awful, and then it drops again. Taking one tablet, waiting 15 minutes, and reassessing gives you much better control.
Another mistake is testing too soon. Testing at 5 or 10 minutes gives you a false reading and makes you think you need more tablets when you do not. Set a timer on your phone for 15 minutes so you do not guess.
A third mistake is taking glucose tablets with a large meal or right after eating. The food in your stomach slows how fast the tablets work, so they may not raise your blood sugar as quickly as you expect. If you are eating, wait until you finish before treating a low, or take the tablets on an empty stomach first and eat a snack afterward.
Frequently Asked Questions
Can I take glucose tablets with food?
Glucose tablets work fastest on an empty stomach. If you have just eaten a meal, the food slows how fast the tablets raise your blood sugar. If you are low and hungry, take the tablets first, wait 15 minutes, retest, and then eat a snack if you want to. If you are in the middle of a meal, finish eating and then test—the food you are already eating may bring your blood sugar up enough.
What if I take too many glucose tablets by accident?
Your blood sugar will go high, usually within 30 to 60 minutes. Drink water, move around if you can, and retest in an hour. If you take insulin, you may need to take a small dose to bring it back down, but do not do this without talking to your doctor first. To prevent this, keep only a few tablets with you at a time and store the rest at home.
Do glucose tablets work the same for everyone?
No. Body weight, stomach contents, medications, and how sensitive you are to insulin all change how much your blood sugar rises from one tablet. You may need to experiment to find your own pattern—some people need one tablet, others need two or three. Keep a record for a week or two to see what works for you.
Can I use glucose tablets to prevent a low blood sugar?
Glucose tablets are meant to treat a low that has already happened, not to prevent one. If you feel a low coming on—shaky, sweaty, or anxious—test first to confirm your blood sugar is actually low. If it is, take a tablet. If you are not sure, testing is safer than guessing.
How long do glucose tablets last once I open the bottle?
Glucose tablets stay good for years if kept in a cool, dry place. Once you open the bottle, they are still fine as long as you keep the cap on and store them away from heat and humidity. Check the expiration date on the bottle—that is the real limit, not how long the bottle has been open.