Glucagon is a hormone your body naturally produces to raise blood sugar. As a medication, it’s most commonly used as an emergency rescue treatment for severe low blood sugar (hypoglycemia) in people with diabetes. It also has lesser-known roles in medical imaging and as a treatment for certain types of drug overdoses.
How Glucagon Works in Your Body
Glucagon’s primary job is to get stored sugar out of your liver and into your bloodstream. Your liver keeps a reserve of glucose packed into a storage molecule called glycogen. When glucagon arrives at liver cells, it triggers a chain reaction that breaks glycogen apart and releases glucose into the blood. This process peaks within about 15 minutes and can sustain your blood sugar for up to three hours.
The hormone works as a direct counterbalance to insulin. While insulin pulls sugar out of your blood and into cells, glucagon pushes it back out of storage. In people with diabetes who use insulin, this balancing act can go wrong. Too much insulin, a skipped meal, or unexpected exercise can crash blood sugar to dangerous levels, and that’s where glucagon as a medication comes in.
Emergency Treatment for Severe Low Blood Sugar
The most widespread use of glucagon is rescuing someone from a severe hypoglycemic episode. The American Diabetes Association defines severe hypoglycemia as a blood sugar drop that causes altered mental or physical status, meaning the person needs help from someone else to recover. At blood sugar levels below 54 mg/dL, confusion, seizures, and loss of consciousness can occur. If someone can’t swallow juice or glucose tablets safely, glucagon is the go-to treatment.
Once injected or inhaled, glucagon typically raises blood sugar within 10 to 15 minutes. Blood glucose peaks around 45 to 60 minutes after administration, and the effect lasts one to two hours. The vast majority of people regain consciousness within 15 to 20 minutes.
After recovery, the person should eat carbohydrates and protein as soon as they can safely swallow. This step is important because glucagon drains the liver’s glucose reserves, and without food to replenish them, blood sugar can crash again. This rebound drop is one of the main risks to watch for in the two hours following treatment.
Dosing by Age and Weight
For adults and children aged six and older who weigh at least 25 kilograms (about 55 pounds), the standard emergency dose is 1 mg. Children under six or weighing less than 25 kg receive a half dose of 0.5 mg. These doses apply whether the injection goes under the skin, into a muscle, or (in a medical setting) into a vein.
Types of Glucagon Delivery Systems
Glucagon comes in several forms, and the differences matter because an emergency is no time to fumble with complicated instructions.
- Traditional emergency kits contain a vial of powdered glucagon and a syringe of liquid that must be mixed together before injection. This multi-step process is difficult under stress. In simulation studies, only 13% of trained caregivers managed to reconstitute and inject a full dose correctly, and none of the untrained bystanders delivered a complete dose. Two caregivers accidentally injected insulin instead of glucagon because the devices looked similar.
- Nasal powder (Baqsimi) is a needle-free device that delivers a 3 mg dose of dry powder into one nostril with a single press of a plunger. In the same simulation study, 94% of caregivers and 93% of acquaintances delivered a full dose, averaging under 30 seconds. Every untrained participant said they would recommend the nasal version. Caregivers consistently rated it as significantly less complex than the injectable kit.
- Pre-filled auto-injectors (Gvoke) eliminate the mixing step and work like an EpiPen. They reduce errors compared to traditional kits, though they still involve a needle, which can be a barrier for people with needle anxiety.
If you or a family member uses insulin, keeping a glucagon device on hand and making sure household members know where it is and how to use it can be lifesaving. The nasal form is generally the easiest for untrained bystanders.
Use in Medical Imaging
Beyond emergency sugar rescue, glucagon is used in radiology departments as a diagnostic tool. When injected intravenously before certain imaging procedures, glucagon temporarily relaxes the smooth muscle of the digestive tract, reducing the contractions that can blur images. This gives radiologists a clearer view during studies of the esophagus, stomach, and colon.
The effect kicks in rapidly when given intravenously and lasts a predictable length of time depending on dose, making it well-suited for timed imaging sessions. Side effects during diagnostic use are uncommon, mostly limited to mild nausea. Glucagon is considered the preferred drug for these “hypotonic” imaging exams because it’s more predictable and better tolerated than older alternatives.
Treatment for Certain Drug Overdoses
Glucagon plays a role in treating overdoses of beta-blockers, a class of heart and blood pressure medications. In large quantities, beta-blockers dangerously slow the heart rate and lower blood pressure. Glucagon can counteract this because it stimulates the heart through a separate pathway that bypasses the receptors beta-blockers are blocking. It primarily speeds up the heart rate, with effects beginning within minutes of a dose and lasting 10 to 15 minutes.
Because the effect is short-lived, a continuous drip is needed after the initial dose to maintain results. One practical challenge is that hospital pharmacies may not stock enough glucagon to sustain a prolonged infusion. For this reason, glucagon is typically considered a second-line treatment for these overdoses, used alongside other supportive therapies. The most common side effects at these high doses are nausea, vomiting, and elevated blood sugar.
Who Should Not Use Glucagon
Glucagon is not safe for everyone. Three conditions make it contraindicated:
- Pheochromocytoma (a rare adrenal gland tumor): Glucagon can trigger the tumor to release a surge of adrenaline-like hormones, causing a sudden, dangerous spike in blood pressure.
- Insulinoma (an insulin-producing tumor of the pancreas): Glucagon can stimulate the tumor to release even more insulin, which would drive blood sugar lower rather than higher.
- Glucagonoma (a glucagon-producing tumor): Similar to insulinoma, administering glucagon in this context can paradoxically worsen low blood sugar.
All three conditions are rare, but they’re important to disclose to medical professionals. For the vast majority of people with diabetes, glucagon is safe when used as directed for hypoglycemic emergencies.