If your blood sugar drops too low, eat or drink 15 grams of fast-acting carbohydrates right away, then wait 15 minutes and recheck. Blood sugar below 70 mg/dL is considered low, and acting quickly prevents symptoms from getting worse. Here’s exactly what to do, what to eat, and how to keep it from happening again.
Recognize the Early Warning Signs
Low blood sugar triggers a rush of stress hormones that produce unmistakable physical symptoms: shaking, sweating, a rapid heartbeat, sudden anxiety, and intense hunger. These are your body’s early alarm system, and they typically show up when blood sugar dips below 70 mg/dL.
If blood sugar continues to fall, the brain starts running short on fuel. That’s when a second wave of symptoms appears: blurred vision, difficulty concentrating, poor coordination, confusion, slurred speech, and weakness. In severe cases, this can progress to fainting, seizures, or loss of consciousness. The goal is to act during the first wave so you never reach the second.
The 15-15 Rule: Your Immediate Action Plan
The standard approach is simple: eat 15 grams of fast-acting carbohydrates, wait 15 minutes, then check your blood sugar again. If it’s still below 70 mg/dL, repeat with another 15 grams. Any of these will give you roughly 15 grams of quick sugar:
- 3 glucose tablets (the fastest, most predictable option)
- Half a cup (4 ounces) of fruit juice or regular soda
- 6 or 7 hard candies
- 1 tablespoon of sugar (dissolved in water or placed under the tongue)
Resist the urge to raid the kitchen. Overeating during a low will send your blood sugar soaring in the other direction, and you’ll spend the next few hours on a roller coaster. Stick to 15 grams, wait the full 15 minutes, and let your body catch up.
What to Eat After Your Blood Sugar Recovers
Once your reading is back above 70 mg/dL, the fast-acting sugar you just consumed will burn off quickly. Without a follow-up snack, your blood sugar can drop again within an hour or two. Eat something that combines complex carbohydrates with a bit of protein or fat to keep levels stable. Good options include a slice of whole-grain bread, a piece of fruit, a small bowl of whole-grain cereal with milk, or a couple of oat cakes with low-fat cheese.
What Counts as Severe Low Blood Sugar
The American Diabetes Association classifies hypoglycemia into three levels. Level 1 is a reading between 54 and 69 mg/dL, which you can usually treat yourself with the 15-15 rule. Level 2 is anything below 54 mg/dL, a range where brain function starts deteriorating noticeably. Level 3 is defined not by a specific number but by needing someone else’s help: you’re too confused, unconscious, or physically impaired to treat yourself.
If someone near you is having a severe episode and can’t safely swallow food or drink, they need glucagon, a hormone that tells the liver to release stored sugar into the bloodstream. Glucagon is available as a nasal spray (sold as Baqsimi) that requires no mixing or injection. It’s a single-use device: insert the tip into one nostril and press. An injectable version is also available. If neither is on hand and the person is unconscious, call emergency services immediately. Never try to force food or liquid into the mouth of someone who can’t swallow.
Recovery Takes Longer Than You Think
Even after your blood sugar reading looks normal again, your brain needs time to catch up. Research on adults with type 1 diabetes found that reaction times remained impaired for up to 75 minutes after blood sugar was restored to a safe level. More complex thinking tasks stayed affected for about 10 to 40 minutes after recovery. This matters for driving, operating machinery, or making important decisions. Give yourself at least an hour after a significant low before doing anything that requires sharp focus.
Why Blood Sugar Drops in the First Place
For people with diabetes, the most common triggers are too much insulin, a missed or delayed meal, unexpected physical activity, or alcohol consumption. Even a well-managed insulin regimen can occasionally overshoot, especially during exercise or sleep.
People without diabetes can also experience low blood sugar. Reactive hypoglycemia causes a drop one to four hours after eating, often because the body overproduces insulin in response to a high-carbohydrate meal. Other causes include alcohol (which can block the liver from releasing glucose), prior gastric bypass surgery, inherited metabolic conditions, and, rarely, certain types of tumors.
Preventing Lows Before They Happen
Consistent meal timing is the single most effective prevention tool. Eating balanced meals every three to five hours, with a mix of protein, fat, and complex carbohydrates, keeps blood sugar from swinging wildly. If you exercise regularly, check your blood sugar before and after workouts, and keep glucose tablets or juice within reach.
For people on insulin, continuous glucose monitors have changed the game. Modern systems can predict a low before it happens. The simplest versions automatically suspend insulin delivery when sensor-detected glucose drops below a set threshold. More advanced systems, like predictive low-glucose suspend, stop insulin when glucose is trending toward a low. The newest closed-loop systems go further: they reduce background insulin when glucose is predicted to fall below about 112 mg/dL, and cut it off entirely when a reading below 70 mg/dL looks likely. These systems also increase insulin when levels run high, effectively acting as an autopilot between meals.
If you experience lows frequently, especially without a clear trigger like a skipped meal, keeping a log of when episodes occur, what you ate beforehand, and what you were doing can reveal patterns. Recurring lows without an obvious cause are worth investigating, since they sometimes point to medication doses that need adjusting or an underlying condition that hasn’t been identified yet.