If your blood sugar drops below 70 mg/dL, eat or drink 15 grams of fast-acting carbohydrates immediately, then wait 15 minutes and recheck. This simple approach, called the 15-15 rule, is the standard first response recommended by the CDC and the American Diabetes Association. Most mild episodes resolve within minutes when treated quickly, but knowing the full picture helps you stay safe when things get more serious.
How to Recognize Low Blood Sugar
The earliest signs of low blood sugar are physical sensations driven by your body’s stress response: shakiness, a racing or irregular heartbeat, sudden sweating, and intense hunger. These symptoms are your body’s alarm system, and they typically appear when glucose dips to around 70 mg/dL or just below.
If blood sugar continues to fall, the brain starts running short on fuel. That’s when you notice dizziness, confusion, irritability, headache, blurred vision, slurred speech, or extreme fatigue. Below 54 mg/dL is considered clinically significant, and at this point, the risk of seizures or loss of consciousness rises sharply. Severe hypoglycemia is defined not by a specific number but by the inability to treat yourself, meaning you need someone else’s help.
Low blood sugar can also happen during sleep. Clues include damp pajamas or sheets from sweating, nightmares or crying out, and waking up feeling unusually tired, confused, or irritable.
The 15-15 Rule: Step by Step
As soon as you suspect low blood sugar, check your level if you can. If it’s under 70 mg/dL, or you can’t check but have symptoms, follow these steps:
- Eat 15 grams of fast-acting carbohydrates. Good options include 4 glucose tablets, 4 ounces (half a cup) of fruit juice, a tablespoon of honey or sugar, or a small handful of regular (not sugar-free) candy like jelly beans.
- Wait 15 minutes. Give the sugar time to reach your bloodstream. Resist the urge to eat more right away, since overcorrecting can send blood sugar too high.
- Recheck your blood sugar. If it’s still below 70 mg/dL, repeat the process: another 15 grams of carbs, another 15-minute wait.
- Eat a balanced follow-up meal or snack. Once your reading is back in your target range, have something with both protein and carbohydrates. A handful of crackers with peanut butter, cheese and whole-grain bread, or a small meal works well. This prevents a second drop.
Stick with fast-acting carbs for the initial treatment. Foods high in fat or fiber, like chocolate bars, slow down sugar absorption and won’t raise your glucose fast enough when it matters.
What to Do in an Emergency
If someone with low blood sugar loses consciousness, has a seizure, or is too confused to swallow safely, do not try to put food or liquid in their mouth. This is a choking risk. Call emergency services and use glucagon if it’s available.
Glucagon is a hormone that signals the liver to release stored sugar into the bloodstream. It now comes in several forms that don’t require medical training to use. A nasal powder (Baqsimi) is administered by inserting the tip into one nostril and pressing the plunger. The person doesn’t need to inhale. An auto-injector (Gvoke HypoPen) works like an EpiPen: you press it against the outer thigh, upper arm, or lower abdomen and it injects automatically. Traditional glucagon kits require mixing a powder with liquid before injecting, which makes them harder to use under stress.
After receiving glucagon, the person should be rolled onto their side in case of vomiting. Most people regain consciousness within 10 to 15 minutes. Once they can swallow safely, give them a snack or meal to replenish the glucose their liver just released.
Preventing Low Blood Sugar at Night
Nocturnal lows are particularly dangerous because you’re asleep and may not notice symptoms. A study of adults with type 1 diabetes on intensive insulin therapy found that 71% of nighttime low blood sugar episodes occurred when no bedtime snack was eaten. When participants ate a snack containing protein or a standard mix of carbs before bed, nighttime lows were eliminated entirely.
The need for a bedtime snack depends on your glucose level before sleep. If your reading is above 180 mg/dL, a snack is generally unnecessary. Between roughly 126 and 180 mg/dL, any small snack helps. Below 126 mg/dL, a snack with protein, such as yogurt, cheese and crackers, or a glass of milk, is the stronger choice. A continuous glucose monitor with low-glucose alerts adds another layer of protection by waking you before levels become dangerous.
When You Stop Feeling the Warning Signs
Some people with diabetes lose the ability to sense when their blood sugar is dropping. This condition, called hypoglycemia unawareness, happens when repeated low episodes train the brain to adapt to lower glucose levels. Over time, the body stops producing the normal stress-hormone response (the shakiness, sweating, and racing heart) that would otherwise alert you. Without those early warnings, blood sugar can plummet to dangerous levels before you realize anything is wrong.
The good news is this process is reversible. Research shows that strictly avoiding any hypoglycemic episodes for just two to three weeks can reset the body’s alarm threshold back to a healthier level. Practically, this means working with your care team to adjust your glucose targets upward temporarily, fine-tuning insulin timing or type, and relying on continuous glucose monitoring to catch drops you can’t yet feel. Over those weeks, the warning symptoms gradually return.
Low Blood Sugar Without Diabetes
People without diabetes can also experience low blood sugar, though it’s less common. The most frequent type is reactive hypoglycemia, where glucose drops a few hours after eating, often after a meal heavy in refined carbohydrates. This can also occur after gastric bypass surgery, when food moves through the stomach too quickly and triggers an exaggerated insulin response.
For reactive hypoglycemia, the management approach focuses on dietary changes: eating smaller, more frequent meals, choosing foods with a lower glycemic index, and avoiding excess sugar, alcohol, and caffeine. In rarer cases, persistent low blood sugar can signal an insulin-producing tumor called an insulinoma, which typically requires surgical removal. If you experience repeated episodes of low blood sugar and don’t have diabetes, the standard diagnostic criteria involve confirming three things together: a blood glucose below 55 mg/dL, symptoms consistent with low blood sugar, and resolution of those symptoms once glucose is corrected.
Keeping a Pattern From Repeating
A single low blood sugar episode is worth noting. Repeated episodes are a signal that something in your routine needs adjusting. Track when lows happen, what you ate beforehand, how much you exercised, and what medications you took. Patterns often emerge quickly: a low every afternoon might mean your lunchtime insulin dose is too high, while lows after exercise might mean you need a pre-workout snack or a temporary reduction in insulin.
Continuous glucose monitors are especially useful here, since they record glucose data around the clock and can reveal trends you’d miss with fingerstick checks alone. Sharing this data with your care team makes it far easier to pinpoint the cause and make targeted changes rather than guessing.