If your blood sugar is below 70 mg/dL, eat or drink 15 grams of fast-acting carbohydrates immediately, then wait 15 minutes and recheck. This is called the 15-15 rule, and it’s the standard first response whether you have diabetes or not. The goal is to bring glucose back into a safe range quickly without overshooting.
How to Recognize Low Blood Sugar
Your body sends early warning signals when glucose drops too low. The first signs are usually physical: shakiness, sweating, a fast or irregular heartbeat, sudden hunger, and pale skin. You might also feel anxious, irritable, or lightheaded, or notice tingling in your lips, tongue, or cheeks.
If blood sugar continues to fall, the symptoms shift from physical to mental. You may have trouble concentrating, feel confused, lose coordination, or notice blurry or tunnel vision. Speech can become slurred. These changes happen because your brain depends heavily on glucose for fuel, and it’s not getting enough.
At the most severe stage, a person can lose consciousness or have a seizure. This is a medical emergency. If someone near you becomes unresponsive from low blood sugar, call 911 right away.
The 15-15 Rule, Step by Step
As soon as you feel symptoms or see a reading below 70 mg/dL on your meter, eat 15 grams of fast-acting carbohydrates. Good options include:
- 3 glucose tablets
- Half a cup (4 ounces) of fruit juice or regular soda
- 6 or 7 hard candies
- 1 tablespoon of sugar
Wait 15 minutes, then check your blood sugar again. If it’s still under 70 mg/dL, repeat: another 15 grams of carbs, another 15-minute wait. Keep cycling through these steps until your reading is back in your target range.
The reason you use fast-acting carbs rather than, say, a sandwich is speed. Glucose tablets and juice enter your bloodstream within minutes. Foods with fat or protein slow digestion, which is exactly what you don’t want when your brain is running low on fuel. Save the balanced meal for after you’ve stabilized.
What to Eat After You’ve Stabilized
Once your blood sugar is back above 70 mg/dL, the job isn’t done. Fast-acting carbs burn off quickly, and without a follow-up snack or meal, you risk dropping again. Eat something that combines complex carbohydrates with protein and healthy fat within the next 30 to 60 minutes. This combination slows digestion and keeps your blood sugar more steady.
Practical choices include nuts (which naturally contain carbs, protein, and fat together), a small serving of Greek yogurt, cottage cheese with fruit, eggs with toast, or a handful of beans. If your next regular meal is close, just make sure it includes that same balance of carbs, protein, and fat. Eating small meals or snacks every two to four hours also helps prevent repeated dips throughout the day.
When Someone Can’t Treat Themselves
Severe low blood sugar can make a person too confused or too drowsy to eat or drink safely. Never try to put food or liquid into the mouth of someone who is losing consciousness, because they could choke. This is when emergency glucagon becomes critical.
Glucagon is a hormone that signals the liver to release stored sugar into the bloodstream. It’s available as an injectable kit and as a nasal spray. If you live with someone who takes insulin, make sure at least one other person in the household knows where the glucagon is stored and how to use it. The nasal spray version requires no mixing or needles, which makes it simpler for a bystander to administer under pressure. If glucagon isn’t available, or the person doesn’t respond within about 15 minutes, call emergency services.
Low Blood Sugar During Sleep
Nocturnal hypoglycemia is especially tricky because you can’t recognize symptoms while you’re asleep. Signs that someone nearby might notice include restless sleep, sweating or clammy skin, trembling, sudden changes in breathing, and nightmares. You might wake up with a headache, feeling exhausted, or with damp sheets and no clear explanation.
Several things raise the risk of overnight drops: skipping dinner, exercising close to bedtime, and drinking alcohol in the evening. Alcohol is a particular concern because it can suppress the liver’s ability to release glucose for hours after your last drink.
A continuous glucose monitor (CGM) is one of the most effective tools for catching nighttime lows. These devices check your glucose every few minutes and can sound an alarm if levels start falling too far. If you’re experiencing frequent overnight episodes, adjusting the timing or dose of evening insulin, in coordination with your care team, is often the core fix.
Why Some People Stop Feeling Symptoms
Repeated episodes of low blood sugar can actually rewire your body’s alarm system. Normally, when glucose drops to around 60 mg/dL, you feel shaky and sweaty, which prompts you to eat. But if low episodes happen often enough, the threshold for triggering those warning signs keeps shifting downward. You might not feel anything at 60, or even at 55. The dangerous part: the blood sugar level that causes you to pass out does not shift. The gap between “I feel fine” and “I’m unconscious” gets narrower and narrower.
This condition, called hypoglycemia unawareness, is reversible in many cases. Research shows that if you can avoid all hypoglycemic episodes for a stretch of time, your body begins to recalibrate and you start feeling symptoms again at higher, safer glucose levels. A CGM helps enormously here, since it catches drops you can’t feel and gives you the data to prevent them in the first place. Newer long-acting insulins and insulin pumps can also reduce the frequency of unexpected lows.
Common Triggers to Watch For
For people with diabetes, the most common cause of low blood sugar is a mismatch between insulin (or certain oral medications) and how much you’ve eaten or how active you’ve been. Taking your usual insulin dose but eating less than normal, or exercising more than usual, can tip the balance. Even something as simple as a delayed meal can be enough.
Low blood sugar can also happen in people without diabetes, though it’s less common. Reactive hypoglycemia causes a drop two to four hours after a meal, typically when the body overproduces insulin in response to a large carbohydrate load. Alcohol, certain medications, hormonal deficiencies, and prolonged fasting are other possible triggers. If you’re experiencing recurring episodes and you don’t have diabetes, that pattern is worth investigating with a healthcare provider, since it can sometimes point to an underlying condition.
Keeping Supplies Within Reach
The single most practical thing you can do is make sure fast-acting carbs are always accessible. Keep glucose tablets in your bag, your car, your desk drawer, and your nightstand. Juice boxes travel well and don’t require refrigeration. If you use glucagon, check the expiration date regularly and replace it before it lapses.
If you wear a medical ID bracelet or carry a card noting your diabetes and medications, first responders can act faster if you’re ever found unresponsive. For people with hypoglycemia unawareness, a CGM with alarms provides an extra safety net that no amount of glucose tablets can replace.