Yes, glucagon raises blood sugar. It is the primary hormone responsible for preventing your blood sugar from dropping too low, and it does this by signaling your liver to release stored glucose into your bloodstream. Glucagon and insulin work as opposing forces: insulin lowers blood sugar after you eat, while glucagon raises it when levels start to fall.
How Glucagon Raises Blood Sugar
Glucagon is produced by alpha cells in your pancreas. When your blood sugar drops to around 68 mg/dL, these cells begin releasing glucagon into your bloodstream. The hormone travels to your liver and triggers two distinct processes that both result in more glucose entering your blood.
The first process is the breakdown of glycogen, which is the stored form of glucose your liver keeps on hand. Your liver holds roughly 100 grams of glycogen at any given time, and glucagon activates enzymes that chop this stored glycogen into individual glucose molecules, which then flow into your bloodstream. This is the fastest way your body raises blood sugar, and it kicks in within minutes.
The second process is the creation of brand-new glucose from non-sugar building blocks like amino acids, lactate, and glycerol. This takes longer but becomes increasingly important during extended fasting, once glycogen stores start running low. Glucagon activates gene programs in liver cells that ramp up this production pathway, ensuring a continued supply of glucose even hours into a fast.
The Insulin-Glucagon Balance
Your body doesn’t rely on either hormone alone. Instead, the ratio between insulin and glucagon determines what your metabolism is doing at any given moment. After a meal, insulin dominates: it pushes glucose into your cells for energy and tells the liver to store any extra as glycogen or fat. Between meals and overnight, glucagon takes over: it signals the liver to break down those stores and release glucose back into the blood.
This ratio shifts constantly throughout the day. It’s lowest during prolonged fasting or starvation, when your body needs maximum glucose release from the liver. It’s highest right after eating a carbohydrate-rich meal, when your body needs to clear glucose from the blood and tuck it away. Think of it as a metabolic seesaw that tips back and forth to keep your blood sugar in a narrow, safe range.
When Glucagon Can’t Do Its Job
Glucagon’s ability to raise blood sugar depends entirely on your liver having something to work with. If glycogen stores are depleted from prolonged fasting, heavy exercise, illness like gastroenteritis, or heavy alcohol consumption, glucagon has far less raw material to convert into glucose. Alcohol is a particularly common culprit because it directly interferes with the liver’s ability to produce new glucose.
This matters most in emergency situations. If someone with diabetes has a severe low blood sugar episode and their liver glycogen is already depleted, glucagon may not raise blood sugar as effectively or as quickly as expected.
Glucagon as Emergency Medicine
Synthetic glucagon is used as a rescue treatment when someone with diabetes has a severe low blood sugar episode and can’t eat or drink safely, often because they’re confused or unconscious. It comes in several forms: traditional injectable kits that require mixing a powder with liquid before injection, pre-filled auto-injectors that work like an EpiPen, and a nasal spray that’s simply puffed into one nostril.
Both injectable and nasal glucagon reach therapeutic levels in the blood within about 5 minutes of administration. In clinical studies, blood sugar typically rose to 70 mg/dL or increased by at least 20 mg/dL within 13 minutes for injectable glucagon and 16 minutes for the nasal version. That 3-minute difference largely disappears in real-world settings, because injectable kits require mixing and preparation that eats into the time advantage. The nasal spray is generally considered easier for bystanders to administer under stress.
Standard adult doses are 1 mg for injectable glucagon and 3 mg for the nasal spray. Children under about 55 pounds typically receive a half dose. These are single-use products, and any leftover medication is discarded.
Side Effects of Glucagon
Nausea and vomiting are the most common side effects. In clinical data, about 6% of glucagon doses were associated with nausea and roughly 10% with vomiting, though many patients in those studies also received anti-nausea medication alongside the glucagon. The nausea tends to be brief, and it’s generally considered a minor tradeoff when someone’s blood sugar is dangerously low. Headache is another commonly reported side effect as blood sugar recovers.
Once someone regains alertness after a glucagon dose, eating a snack with carbohydrates and protein helps stabilize blood sugar and replenish the liver glycogen that glucagon just depleted. Without food, blood sugar can drop again within an hour or two.
What Else Triggers Glucagon Release
Low blood sugar isn’t the only thing that stimulates glucagon. Protein-rich meals cause a significant rise in glucagon, because amino acids from digested protein directly stimulate the alpha cells in the pancreas. This makes biological sense: when you eat pure protein with little carbohydrate, your body needs glucagon to prevent insulin (which also rises after protein intake) from dropping blood sugar too low.
Exercise, stress hormones like adrenaline, and certain gut hormones also stimulate glucagon release. In people with diabetes, this regulation often becomes disordered. Alpha cells may release too much glucagon after meals (contributing to high blood sugar) or too little during lows (making hypoglycemia harder to recover from). This disrupted glucagon signaling is increasingly recognized as a core feature of diabetes, not just a side issue.