Low Blood Sugar
The right fix is plain sugar, and one kind of pill can make it come back
General information from an emergency physician. It adds to your discharge papers and does not replace them or your own doctor. What this site is and isn’t
Key Takeaways:
- Treat a low with 15 grams of fast sugar, wait 15 minutes, then recheck. Glucose tablets or gel work faster than candy, juice, or milk.
- Once the number rises, eat a real snack or meal. This helps prevent another low.
- A low caused by glipizide, glyburide, or glimepiride can return hours later.
About Your Diagnosis and ED Workup
Low blood sugar means the brain is running short of fuel. Shaking, sweating, hunger, worry, and a pounding heart are warning signs. Confusion, weakness, seizure, or passing out mean the brain is being affected.
Repeated lows can make warning signs quieter even when danger remains. Avoiding more lows for a few weeks can bring some warning back. Your personal low number comes from your meter target and prescriber, so this page does not set one.
First Steps and Evidence-Based Home Care
The 15-15 rule
For someone who is awake and can safely swallow:
- Take 15 grams of fast sugar. Glucose tablets or gel work faster than juice, candy, or milk.
- Wait 15 minutes, then recheck.
- If still low, take 15 grams again and recheck.
- Once the sugar is normal, eat a real snack or meal.
The snack or meal helps while insulin or another medicine is still working. Do not use chocolate, candy bars, or milk first because fat slows sugar absorption.
Weight-loss surgery exception: The 15-gram fix can cause a rebound low. Follow your own plan. Smaller meals with less fast-digesting carbohydrate, more protein and fiber, and a glucose monitor may be used instead.
Never put food, drink, or medicine in the mouth of someone who cannot swallow. Return to the emergency department.
Do not drive until symptoms are gone and a recheck is normal. A low can impair judgment and reaction time.
Keep diabetes pills away from children. One sulfonylurea pill can cause a dangerous low in a small child up to 18 hours later. Do not skip the next insulin dose on your own; review dose and timing with the prescriber.
Timeline and Expected Recovery Course
How long a low lasts depends on the cause:
- A low from glipizide, glyburide, or glimepiride can come back any time in the next 24 hours, most often in the first several hours and overnight. Keep eating regular meals and snacks today, check again before bed, and treat any new low the same way: 15 and 15.
- A low after alcohol, especially without food, can be delayed.
- A child who swallowed one of these pills can look well and still become low up to 18 hours later.
- Avoiding lows for a few weeks can restore some warning signs.
Emergency Red Flags: Return Immediately
Return to the emergency department for:
- Confusion, seizure, inability to wake, or symptoms that do not clear quickly and fully after treatment.
- A low that returns after sugar, a recheck, and a snack or meal, or sugar that will not stay up.
- A low after drinking alcohol, especially without food.
- Any diabetes-medicine overdose, whether accidental or intentional and whether in an adult or child.
This list does not cover everything. If something feels wrong or is worsening, return to the emergency department. If someone cannot safely swallow, give nothing by mouth.
Reviewed September 3, 2026