A glucagon injection is an emergency treatment that rapidly raises blood sugar in people with diabetes who are experiencing severe hypoglycemia (dangerously low blood sugar). Glucagon is a hormone your body naturally produces, and when injected, it signals the liver to release its stored sugar into the bloodstream. Most unconscious patients wake up within 15 minutes of receiving a dose, with blood sugar typically peaking around 136 to 138 mg/dL within 30 minutes.
How Glucagon Works in the Body
Your liver stores sugar in a form called glycogen, essentially a reserve fuel tank your body can tap into between meals. Glucagon is the hormone that tells the liver to break open that reserve and release sugar into the blood. Your pancreas produces glucagon naturally, but during a severe low blood sugar episode, the body may not release enough on its own, especially in people taking insulin or certain diabetes medications.
An injected dose of glucagon mimics this natural signal on a much larger scale, flooding the liver with the instruction to release sugar fast. When given into a muscle, blood sugar starts rising within about 8 to 10 minutes. When given through an IV, the response begins in roughly one minute. The effect lasts anywhere from 12 to 32 minutes depending on the dose and how it’s delivered.
One important limitation: glucagon only works if the liver actually has stored sugar to release. People who have been fasting for an extended period, are malnourished, or have been drinking heavily may have depleted their glycogen stores. In those situations, glucagon will be far less effective.
When It’s Used
Glucagon is primarily used when someone with diabetes has blood sugar low enough to cause confusion, seizures, or unconsciousness, and they can’t safely eat or drink anything with sugar. This is the scenario it’s designed for: the person can’t help themselves, and someone nearby needs to act. It’s a bridge treatment meant to raise blood sugar enough for the person to regain consciousness while emergency help is on the way.
Glucagon also has a secondary use as a diagnostic tool. Doctors sometimes use it during imaging procedures to temporarily relax the muscles of the stomach and intestines, making certain scans easier to read. But for most people searching this term, the emergency use is what matters.
Available Forms
Glucagon comes in several forms, and the differences between them are mostly about ease of use in a high-stress moment.
- Traditional emergency kits require you to mix a powder with a liquid before injecting. You draw up the solution into a syringe and inject it into the upper arm, thigh, or buttocks. This takes some practice and can feel complicated when you’re panicking.
- Pre-filled auto-injectors work like an EpiPen. The glucagon is already in liquid form, ready to inject without any mixing.
- Nasal powder (sold as Baqsimi) is sprayed into one nostril. You insert the tip, press the plunger until a green line disappears, and the dose is delivered. The person doesn’t even need to inhale it. This is approved for patients age 4 and older and is often the easiest option for caregivers who are uncomfortable with needles.
Each nasal device contains one single dose and can’t be reused. The injectable kits are also single-use.
Dosing for Adults and Children
The standard adult dose is 1 mg, injected into the upper arm, thigh, or buttocks. Children weighing less than 55 pounds (25 kg), or those under 6 years old with unknown weight, receive a half dose of 0.5 mg. The nasal spray delivers a fixed 3 mg dose regardless of age (for those 4 and older).
If there’s no response after 15 minutes, a second dose can be given using a new kit or device while you wait for emergency medical help.
What to Do After Giving Glucagon
Immediately after administering glucagon, turn the person onto their side. Nausea and vomiting are common side effects, and the side position prevents choking if the person vomits while still unconscious or groggy.
Once the person wakes up and can swallow safely, the next step is food. If their blood sugar is still below 70 mg/dL, start with a fast-acting sugar source like apple juice or regular soda. Once blood sugar climbs above 100 mg/dL, offer something more substantial that combines carbohydrates and protein, like crackers with cheese or a sandwich. This helps stabilize blood sugar after the glucagon’s relatively short effect wears off.
Glucagon’s blood sugar boost is temporary. Without follow-up food, blood sugar can drop right back down once the liver’s stored sugar is used up.
Side Effects
The most common side effects are nausea and vomiting, which tend to occur more frequently at higher doses. A 2 mg dose causes noticeably more nausea than a 1 mg dose. Some people experience a headache or temporary rise in heart rate. These effects are generally short-lived and resolve on their own.
In rare cases, allergic reactions can occur, including rash, difficulty breathing, or a drop in blood pressure. Anyone who has had a previous allergic reaction to glucagon should not receive it again.
Who Should Not Receive Glucagon
Glucagon is not safe for everyone. People with a pheochromocytoma (a rare tumor of the adrenal gland) should not receive it because glucagon can trigger a dangerous spike in blood pressure by stimulating the tumor to release stress hormones. People with an insulinoma (a tumor of the pancreas that overproduces insulin) should also avoid it. Glucagon may initially raise blood sugar in these patients, but the spike then triggers the tumor to dump even more insulin, causing blood sugar to crash lower than before.
People with a glucagonoma, a rare glucagon-producing tumor, should not receive it when it’s being used as a diagnostic aid, again because of the risk of a rebound blood sugar drop.
Storage and Shelf Life
Traditional glucagon kits (the kind you mix before injecting) can be stored at room temperature, between 68°F and 77°F, for up to 24 months. Keep them away from freezing temperatures and out of direct light. Once you mix the powder with the liquid, use it immediately and throw away any leftover solution.
Nasal glucagon and pre-filled pens have their own expiration dates printed on the packaging. Whichever form you carry, check the expiration date periodically. An expired kit in an emergency is almost as unhelpful as no kit at all. Many people find it useful to set a calendar reminder a month before expiration so they have time to get a replacement.
Practical Tips for Caregivers
If you live with or care for someone at risk of severe low blood sugar, know where the glucagon is stored and how to use it before an emergency happens. Practice with a training device if one is available, or at minimum read the instructions thoroughly. In the moment, with an unconscious person in front of you, is not when you want to be reading fine print for the first time.
Keep the kit in a consistent, accessible location that other household members know about. If the person at risk spends time at work, school, or with other caregivers, consider having a second kit in those locations. Let the people around them know it exists and where to find it.