If your blood sugar is low (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 recommended by the CDC. If your level is still under 70 mg/dL after 15 minutes, repeat with another 15 grams. Keep going until your blood sugar is back in your target range.
What Counts as 15 Grams of Fast-Acting Carbs
You need something your body can absorb quickly, not a sandwich or a granola bar. Any of these will give you roughly 15 grams of fast-acting carbohydrate:
- 3 glucose tablets (the most precise 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 straight)
Glucose tablets are worth keeping in your bag, car, and nightstand because they’re pre-measured and won’t tempt you to over-treat. When people grab a full glass of juice or a handful of candy, they often consume far more than 15 grams, which can send blood sugar swinging too high.
What to Eat After Your Blood Sugar Stabilizes
Once your blood sugar is back above 70 mg/dL, the fast-acting sugar you just consumed will burn off quickly. Without a follow-up snack or meal, you risk dropping again. Eat something that combines protein with complex carbohydrates: crackers with peanut butter, cheese with whole-grain bread, or a small balanced meal if it’s close to mealtime.
For longer-term prevention, especially if you experience reactive hypoglycemia (low blood sugar that happens a few hours after eating), focus on high-fiber foods like whole grains, fruits, and vegetables. Eating smaller meals spaced about three hours apart throughout the day helps keep blood sugar steady. Avoid sugary foods and processed simple carbohydrates like white bread on an empty stomach, since they cause a rapid spike followed by a drop.
Recognizing the Symptoms
Low blood sugar typically announces itself with early warning signs: a fast heartbeat, shaking, sweating, sudden hunger, dizziness, and a wave of anxiety or irritability that seems to come from nowhere. These symptoms are your body’s adrenaline response, and they’re your cue to check your blood sugar and treat immediately.
If blood sugar continues to fall, the symptoms shift from uncomfortable to dangerous. You may feel weak, have trouble walking or seeing clearly, become deeply confused, or act in ways that seem strange to people around you. Severe low blood sugar, defined as below 54 mg/dL, can cause seizures or loss of consciousness.
When You Can’t Treat Yourself
If someone with low blood sugar is unconscious, seizing, or too confused to swallow safely, do not try to put food or liquid in their mouth. This is when emergency glucagon is used. Glucagon is a hormone that signals the liver to release stored sugar into the bloodstream, and it’s available as a nasal spray that anyone can administer.
The nasal version requires no priming and no inhalation. You simply insert the device into one nostril and press the plunger. It delivers a single 3-milligram dose. If there’s no response after 15 minutes, a second dose can be given. Call emergency services immediately after administering it. Once the person is alert and able to swallow, give them a fast-acting sugar source followed by a snack like crackers with cheese or peanut butter.
If you take insulin or medications that can cause lows, keep a glucagon kit accessible and make sure the people you live with or spend time with know where it is and how to use it.
Low Blood Sugar During Sleep
Nighttime lows are especially tricky because you’re asleep and can’t notice the warning signs. Your body’s normal hormonal responses to low blood sugar are actually blunted during sleep, meaning you produce less of the hormones that would otherwise wake you up and raise your glucose. Common triggers include skipping dinner, exercising close to bedtime, drinking alcohol in the evening, and taking certain types of insulin that peak hours after the dose.
Signs that you may have had a nighttime low include waking up with a headache, feeling unusually tired, or finding damp sheets from sweating. If you suspect this is happening, setting an alarm to check your blood sugar in the early morning hours (around 2 to 3 a.m.) can help you catch the pattern. A continuous glucose monitor with a low-glucose alarm is the most reliable solution for people who experience frequent nighttime episodes, since it checks your levels every few minutes and can wake you before things get dangerous.
Partners and roommates should learn the signs of nighttime hypoglycemia so they can help if you become unresponsive.
Why Some People Stop Feeling the Warning Signs
Repeated episodes of low blood sugar can actually train your brain to stop sounding the alarm. This is called hypoglycemia unawareness, and it happens because the brain adapts to lower glucose levels over time, resetting its threshold for triggering warning symptoms. The adrenaline response that normally causes shaking, sweating, and a pounding heart becomes muted. Levels of epinephrine, the key hormone behind those early warning signs, drop significantly after a person has experienced recent lows.
This creates a dangerous cycle: each undetected low makes the next one harder to detect. People with hypoglycemia unawareness can drop to dangerously low levels without feeling anything unusual until they’re already confused or impaired. A continuous glucose monitor is particularly valuable here, since it provides an external warning system that doesn’t rely on your body’s dulled internal signals. Carefully avoiding all lows for a period of several weeks can sometimes help restore awareness by allowing the brain’s glucose-sensing threshold to reset back to normal levels.
Driving and Low Blood Sugar
Driving with low blood sugar is comparable to driving impaired. Your reaction time, vision, and judgment are all affected. Canadian diabetes guidelines, which are among the most specific on this topic, recommend not starting the car if your blood sugar is below about 72 mg/dL (4.0 mmol/L). If a low hits while you’re already driving, pull over to a safe location and remove the keys from the ignition before treating.
Here’s the part most people don’t realize: even after you treat a low and your numbers come back up, your cognitive function takes time to fully recover. The recommendation is to wait at least 40 minutes after your blood sugar has risen to at least 90 mg/dL (5.0 mmol/L) before driving again. Keep glucose tablets in your car so you’re never caught without a way to treat a low on the road.