If your blood sugar drops below 70 mg/dL, the fastest fix is eating 15 grams of fast-acting carbohydrates, waiting 15 minutes, and checking again. This approach, known as the 15-15 rule, is the standard first response whether you’re at home, at work, or anywhere else. But treating a low in the moment is only part of the picture. Preventing future episodes and knowing when a low becomes dangerous matter just as much.
Recognizing the Signs
Low blood sugar produces two waves of symptoms, and learning to catch the first wave gives you more time to act. The early signs come from your body’s stress response: sweating, a pounding or racing heart, shaky hands, anxiety, and sudden intense hunger. These symptoms are your alarm system firing, telling you glucose is dropping and you need fuel.
If blood sugar keeps falling, the symptoms shift. Your brain starts running short on its primary energy source, and the signs become neurological: confusion, difficulty concentrating, irritability, slurred speech, and in severe cases, loss of consciousness or seizures. By this stage, you may not be able to treat yourself, which is why acting on early symptoms is so important and why the people around you should know what to look for.
The 15-15 Rule for Mild Lows
When you feel symptoms or your monitor shows a reading below 70 mg/dL, eat or drink 15 grams of fast-acting carbohydrates. Good options include four glucose tablets, a small tube of glucose gel, four ounces of juice, or a regular (not diet) soda. These are high on the glycemic index, meaning they hit your bloodstream quickly.
Wait 15 minutes, then recheck. If you’re still below 70, repeat with another 15 grams. Keep cycling through these steps until your blood sugar climbs back into your target range. Once it does, eat a small meal or snack that includes some protein or fat to help stabilize your levels and prevent another dip. A handful of nuts with crackers, cheese and whole-grain bread, or peanut butter on toast all work well.
One common mistake is over-treating. When you feel shaky and anxious, the urge to eat everything in sight is strong. But flooding your system with carbohydrates can send blood sugar rocketing in the other direction. Stick to 15 grams at a time.
When Someone Can’t Treat Themselves
Severe lows, where a person is unconscious, confused, or unable to swallow safely, require glucagon. This is a hormone that signals the liver to release stored glucose into the bloodstream. Glucagon is available by prescription in two main forms: an injectable kit and a nasal spray.
The nasal spray has become the preferred option for most caregivers. In a simulated emergency study, untrained users were just as successful administering the nasal version as people who had been specifically trained. The injectable kit, by contrast, had zero successful doses among untrained users. It requires mixing a powder with liquid and drawing it into a syringe, steps that are difficult to execute under stress. If someone in your household uses insulin, having a nasal glucagon device on hand and making sure family members know where it is can be lifesaving.
If glucagon isn’t available and the person is unconscious or seizing, call emergency services. Never try to put food or liquid in the mouth of someone who can’t swallow.
Preventing Lows if You Have Diabetes
Treating a low is reactive. The real goal is having fewer of them in the first place. Several strategies help.
Continuous glucose monitors (CGMs) are one of the biggest advances. These small sensors, worn on the arm or abdomen, track glucose levels around the clock and alert you when levels are trending down, often before symptoms appear. When paired with an insulin pump, some systems go a step further. Predictive low-glucose suspend technology automatically stops basal insulin delivery when it calculates that your glucose will drop below a set threshold within 30 minutes. Insulin delivery resumes on its own once levels start rising. In real-world data, this feature significantly reduced time spent in the low range, particularly overnight.
Beyond technology, consistent habits make a difference. Eating meals and snacks on a regular schedule, checking blood sugar before and after exercise, adjusting insulin doses before physical activity, and being cautious with alcohol (which can lower blood sugar for hours after drinking) all reduce your risk.
Nighttime Lows
Low blood sugar during sleep is especially risky because you can’t feel or respond to symptoms the way you would while awake. If you take insulin and notice morning lows or wake up with headaches and damp sheets, a bedtime snack that combines carbohydrates with protein or fat can help. Think a small bowl of cereal with milk or an apple with peanut butter. If nighttime lows happen regularly, it typically signals that your insulin dose or timing needs adjusting rather than just adding a snack.
Low Blood Sugar Without Diabetes
You don’t need to have diabetes to experience low blood sugar. Reactive hypoglycemia causes a glucose drop two to four hours after eating, particularly after meals high in sugar or refined carbohydrates. Your body overproduces insulin in response to a rapid blood sugar spike, and the overcorrection sends levels too low. This is also common after certain stomach surgeries.
The dietary approach centers on keeping blood sugar steady throughout the day rather than letting it spike and crash:
- Eat every three hours with small, balanced meals rather than two or three large ones.
- Pair carbohydrates with protein at every meal. Adding meat, eggs, cheese, or legumes to a carb-containing meal slows digestion and blunts the insulin spike.
- Choose low-glycemic carbohydrates. Swap white bread for seeded or sourdough, white rice for basmati or brown rice, and sugary cereals for porridge or muesli. These release glucose more slowly.
- Limit sugary foods and drinks. Sweets, honey, jam, full-sugar sodas, and fruit juice cause the rapid blood sugar spikes that trigger the crash.
- Include fiber. Vegetables, whole grains, and legumes all slow glucose absorption.
- Limit alcohol and consider cutting back on caffeine, as both can affect blood sugar regulation.
These changes don’t require a complete diet overhaul. Even small swaps, like choosing boiled new potatoes with their skins instead of mashed white potatoes, or eating wholegrain pasta cooked al dente instead of regular white pasta, shift the glycemic load of a meal meaningfully.
When Warning Signs Disappear
Some people who experience frequent lows gradually lose their ability to feel them. This condition, called hypoglycemia unawareness, develops because repeated low episodes recalibrate the brain’s glucose-sensing system. The usual stress hormones that trigger sweating, shaking, and hunger become blunted. As few as one or two episodes of significant hypoglycemia can start this process.
The good news is that it can be at least partially reversed. The key strategy is scrupulous avoidance of low blood sugar for a sustained period. Over weeks to months without lows, the brain’s alarm system gradually resets and warning symptoms begin to return. CGMs and automated insulin delivery systems make this avoidance much more achievable than it used to be, since technology can catch drops that a person with blunted awareness would miss. Structured education programs that teach people to recognize subtle internal cues have also proven effective at improving awareness.
For people with severe, frequent lows that don’t respond to other approaches, pancreas or islet cell transplantation remains an option. These procedures restore the body’s own insulin and glucagon production and can virtually eliminate hypoglycemia, with awareness often improving almost immediately after transplant.
When a Low Becomes an Emergency
Most mild lows resolve quickly with the 15-15 rule. But certain situations call for emergency care: if someone loses consciousness or has a seizure, if confusion or neurological symptoms persist after treatment, or if a low has no obvious cause in someone whose blood sugar has previously been well controlled. A sudden unexplained episode in a person without a history of lows needs medical evaluation, since it can signal an underlying condition. Similarly, lows caused by accidentally taking too much of a blood sugar-lowering medication can be prolonged and unpredictable, sometimes requiring hours of monitoring.