Known brand names include GlucaGen.
An emergency shot for severe low blood sugar in people with diabetes, usually given by a family member or caregiver because the person is too low to treat themselves. It makes the liver release stored sugar, and it is also used in imaging to hold the gut still for X-ray exams.
Glucagon is a lab-made copy of a hormone the pancreas makes, with the same structure as human glucagon. It attaches to glucagon receptors in the liver, which makes the liver break down its stored sugar, called glycogen, and send that sugar into the blood. Outside the liver, it relaxes the smooth muscle of the stomach and the small and large bowel. That relaxation is what holds the gut still for X-ray exams.
After a shot under the skin, blood sugar starts to climb within about 10 minutes and peaks about 30 minutes later. The body clears the drug itself quickly, with a half-life of 8 to 18 minutes, and the person eats once awake to refill the liver's sugar stores and keep the low from returning. Because it depends on those stores, it may not work in people who are starving, have adrenal gland problems, or have had low blood sugar for a long time. It can also make an adrenal tumor called a pheochromocytoma release stress hormones that sharply raise blood pressure, and it can push an insulin-making tumor of the pancreas to cause low blood sugar.
Glucagon is an emergency medicine for severe hypoglycemia, a dangerously low blood sugar in a person with diabetes. At that stage the person may be confused, pass out, or have a seizure, so someone else has to help them recover. It is meant to raise blood sugar quickly until the person wakes up and can swallow food. It has a second use in imaging, where it briefly stops movement of the stomach and bowel during certain X-ray exams.
Family members or caregivers learn ahead of time how to mix and inject it, and people who often have low blood sugar keep a kit with them. It is approved for adults and children with diabetes, and someone should call for emergency help right after giving it. Once the person is awake and able to swallow, they eat sugar so the low does not come back. The X-ray use takes place in a medical facility, where a doctor or nurse gives it, and it is approved only for adults.
Nausea and vomiting are what people notice most, along with headache, dizziness, weakness, pale skin, sleepiness, diarrhea, and redness or swelling where the shot went in. Blood pressure can drop, or it can rise along with a faster heartbeat. The label treats serious allergic reactions as dangerous, including rash, trouble breathing, and low blood pressure. It also warns of a sharp rise in blood pressure in people with an adrenal tumor and of low blood sugar in people with certain pancreas tumors.