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 protocol, called the 15-15 rule, is the standard first response for low blood sugar. How you handle the next few minutes depends on how low your levels have fallen and how your body is responding.
How to Recognize a Blood Sugar Drop
Your body sends out two waves of warning signs when blood sugar falls. The first wave comes from a rush of adrenaline as your body tries to correct the problem on its own. You’ll feel shaky, sweaty, and anxious. Your heart may race, and you’ll likely feel suddenly and intensely hungry. These early symptoms are your clearest signal to act.
If blood sugar keeps falling, the second wave of symptoms comes from your brain running low on fuel. This stage looks different: blurred vision, difficulty concentrating, confusion, poor coordination, slurred speech, and weakness. Some people describe tingling in their lips or hands. At the most extreme end, untreated low blood sugar can cause seizures or loss of consciousness. The goal is to catch it during that first wave, when you’re still alert enough to treat yourself.
The 15-15 Rule, Step by Step
The CDC recommends a straightforward approach: consume 15 grams of fast-acting carbohydrates, wait 15 minutes, then check your blood sugar again. If it’s still below 70 mg/dL, repeat the process. Once your levels return to normal, eat a small meal or snack to keep them stable.
Any of these will give you roughly 15 grams of quick carbohydrates:
- 3 glucose tablets
- Half a cup (4 ounces) of fruit juice or regular soda
- 6 or 7 hard candies
- 1 tablespoon of sugar
Glucose tablets are the most precise option because each one contains a measured amount. Juice and soda work well too, but make sure it’s the regular version, not diet. The point is speed: you want simple sugar that hits your bloodstream fast. Foods with fat or protein, like chocolate or peanut butter crackers, slow digestion and won’t raise your levels quickly enough in the moment.
Understanding Blood Sugar Levels
Not all low blood sugar episodes are the same. Clinically, there are three levels. Level 1 is a reading between 54 and 69 mg/dL. This is where most people notice early symptoms and can treat themselves with the 15-15 rule. Level 2 is a reading below 54 mg/dL, which is more serious and requires prompt treatment. Level 3 is any episode where you’re too impaired to treat yourself and need someone else’s help, regardless of the exact number on the meter.
The distinction matters because a mild dip that you catch early is a routine event for many people with diabetes, while a drop below 54 mg/dL or one that causes confusion signals something that needs closer attention from your care team.
When Someone Else Needs to Help
If blood sugar falls low enough to cause confusion, seizures, or loss of consciousness, the person can’t safely eat or drink. Trying to put food or liquid in the mouth of someone who can’t swallow creates a choking risk. This is when emergency glucagon becomes critical.
Glucagon is a hormone that tells your liver to release stored sugar into the bloodstream. It’s available in several forms designed for non-medical people to use in an emergency. A nasal spray version delivers a dose of powdered glucagon into one nostril. It doesn’t need to be inhaled; just inserting the tip and pressing the plunger is enough. Injectable versions come as prefilled auto-injectors, similar in concept to an EpiPen, and can be given in the thigh, abdomen, or upper arm. If there’s no response after 15 minutes, a second dose can be given.
If you don’t have glucagon available, don’t know how to use it, or the person remains unconscious after a dose, call 911 immediately. Severe hypoglycemia that causes seizures or loss of consciousness is a medical emergency.
Common Triggers for Blood Sugar Drops
For people taking insulin or certain diabetes medications (particularly sulfonylureas), low blood sugar is a known side effect. But timing and lifestyle factors play a big role in when it happens.
Exercise increases how efficiently your muscles use glucose, which can cause blood sugar to drop during or after physical activity. The effect can linger for hours, meaning a workout in the afternoon might trigger a low that evening or overnight. Checking your levels before and after exercise, and having a snack on hand, helps prevent this.
Alcohol is a particularly tricky trigger. Your liver normally keeps blood sugar stable between meals by releasing stored glucose. But when you drink, your liver prioritizes breaking down alcohol over maintaining blood sugar. This trade-off is especially pronounced when you drink without eating. The timing makes it deceptive: hypoglycemia can strike hours after your last drink, and the symptoms of low blood sugar (dizziness, confusion, poor coordination) can look a lot like intoxication, making it easy to miss.
Skipping meals, eating less than usual, or taking too much medication relative to the food you’ve eaten are other common causes. Any time there’s a mismatch between the insulin in your system and the glucose available, a drop becomes more likely.
Preventing Low Blood Sugar at Night
Nighttime lows are especially concerning because you’re asleep and may not notice the warning signs. The Joslin Diabetes Center recommends checking your glucose before bed, either with a fingerstick meter or a continuous glucose monitor. If you exercised that day, you may need to reduce your evening insulin dose, since the blood sugar lowering effect of physical activity can extend into the overnight hours.
Keep glucose tablets, juice, or regular soda on your nightstand so you can treat a low without stumbling to the kitchen. If you’re waking up with headaches, feeling groggy, or noticing damp sheets from sweating, those can be signs of overnight lows you slept through. A continuous glucose monitor with low-alert settings can wake you before levels get dangerously low.
When You Stop Feeling the Warning Signs
Some people with diabetes, especially those who have had the condition for many years or experience frequent lows, gradually lose the ability to feel early symptoms. This is called hypoglycemia unawareness, and it happens because the body’s adrenaline response becomes blunted after repeated episodes. Instead of feeling shaky and sweaty at 65 mg/dL, the first sign might be confusion, erratic behavior, or something noticed by someone else rather than by you.
This is dangerous because it removes your window to self-treat. If you or people around you have noticed episodes where your blood sugar was very low but you didn’t feel it coming, that’s important information for your diabetes care team. The usual approach involves carefully avoiding any lows for several weeks, which can help restore the body’s ability to sense drops again. More frequent glucose monitoring, or switching to a continuous monitor, becomes especially valuable in this situation.