The pancreas has two jobs: it makes digestive enzymes for the gut and hormones for the blood. The hormones come from small clusters of cells called the islets of Langerhans.
Insulin
Beta cells release insulin when glucose rises after a meal. Insulin moves glucose into muscle and fat cells and tells the liver to store it as glycogen.
Glucagon
Alpha cells release glucagon when glucose falls. It makes the liver break down glycogen and build new glucose, keeping blood levels up between meals.
When insulin fails
In type 1 diabetes the beta cells are destroyed, so cells starve and the body burns fat, making ketones and acid. In type 2 diabetes the cells resist insulin and the pancreas cannot keep up.
Normal values
Fasting glucose is normally 70 to 99 mg/dL (3.9 to 5.5 mmol/L), and below 70 mg/dL is low. HbA1c shows the average glucose over about three months.
| Test | Normal | Diabetes |
|---|---|---|
| Fasting glucose | 70 to 99 mg/dL | 126 mg/dL or higher |
| HbA1c | Under 5.7% | 6.5% or higher |
| 2 hours after a 75 g glucose drink | Under 140 mg/dL | 200 mg/dL or higher |
At the bedside
Check a fingerstick glucose in any patient who is confused, sweaty or unresponsive. Low blood sugar is quick to treat and can kill if it is missed.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).