Glucagon

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Spec 7.14

Higher tier

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GlucagonSpec 7.14

In short

Glucagon is a hormone secreted by the pancreas when blood glucose concentration falls too low, for example between meals or during exercise. It acts on the liver, which changes glycogen into glucose and releases it into the blood, so blood glucose concentration rises back to normal. Insulin and glucagon work against each other by negative feedback.

If blood glucose concentration falls too low, for example between meals or during exercise, the pancreas secretes glucagon instead.

Blood glucose concentration falls.
The pancreas secretes glucagon into the blood.
Glucagon acts on the liver. The liver changes glycogen into glucose.
Glucose is released into the blood, so blood glucose concentration rises back to normal.

Insulin and glucagon compared
	Insulin	Glucagon
Released when	Blood glucose is too high	Blood glucose is too low
Acts on	Liver and other cells	Liver
Effect	Glucose into cells, glucose to glycogen	Glycogen to glucose
Result	Blood glucose falls	Blood glucose rises

Insulin and glucagon work against each other. This is negative feedback, and it keeps blood glucose concentration close to normal.

Written and checked against the Edexcel GCSE Biology (1BI0) specification · Updated October 2026

Frequently asked questions

What does insulin do to blood sugar?

Insulin lowers blood sugar. The pancreas secretes insulin into the blood when blood glucose concentration rises, for example after a meal. Insulin makes cells take up glucose from the blood, and in the liver and muscles the glucose is converted into glycogen for storage. Blood glucose concentration then falls back to normal.

How does the body control blood glucose levels?

Higher tier The pancreas controls blood glucose using two hormones. When blood glucose is too high, it secretes insulin, so cells take up glucose and the liver stores it as glycogen. When blood glucose is too low, it secretes glucagon, so the liver changes glycogen into glucose. This negative feedback keeps blood glucose close to normal.

What is the difference between type 1 and type 2 diabetes?

In type 1 diabetes the pancreas does not produce enough insulin, so it is controlled by insulin injections, blood glucose monitoring and diet. In type 2 diabetes the body cells no longer respond properly to insulin. Type 2 is linked to obesity and is controlled by diet, exercise and weight loss, sometimes with medication.

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