Yes, the pancreas produces insulin. The hormone is made in beta cells located in clusters called the islets of Langerhans, scattered throughout pancreatic tissue. Beta cells release insulin in response to rising blood glucose after meals. In type 1 diabetes, the immune system destroys these cells. In type 2 diabetes and prediabetes, the cells remain but the body’s response to their insulin is impaired, and beta cell function eventually declines.
The Pancreas at a Glance
The pancreas is a long, flat organ behind the stomach with two main jobs:
- Exocrine function: producing digestive enzymes that travel through ducts to the small intestine — about 95 percent of pancreatic tissue
- Endocrine function: producing hormones (insulin, glucagon, somatostatin, and others) that travel directly into the bloodstream — about 1 to 2 percent of tissue
The endocrine portion is concentrated in the islets of Langerhans, named after the medical student who first described them in 1869.
Inside an Islet of Langerhans
| Cell Type | Hormone Produced | Approximate Percentage of Islet |
|---|---|---|
| Beta cells | Insulin | 60 to 80 percent |
| Alpha cells | Glucagon | 15 to 20 percent |
| Delta cells | Somatostatin | 3 to 10 percent |
| PP cells | Pancreatic polypeptide | 1 to 5 percent |
| Epsilon cells | Ghrelin | Less than 1 percent |
A healthy adult pancreas contains roughly one million islets, totaling about one to two grams of tissue dedicated to glucose regulation.
How Beta Cells Make Insulin
- Glucose from the bloodstream enters the beta cell through the GLUT-2 transporter
- The cell metabolizes glucose, producing ATP (cellular energy)
- Rising ATP closes a potassium channel (the K-ATP channel)
- This depolarizes the cell membrane
- Voltage-gated calcium channels open; calcium rushes in
- Calcium triggers vesicles containing pre-stored insulin to fuse with the cell membrane
- Insulin is released into the bloodstream
This entire sequence takes seconds. Beta cells maintain a baseline of insulin secretion 24 hours a day, with rapid pulses every 3 to 6 minutes and large surges after meals.
What Insulin Does Once Released
- Muscle: takes up glucose for energy and storage as glycogen
- Liver: stops producing new glucose, stores incoming glucose as glycogen
- Fat (adipose tissue): takes up glucose, suppresses fat breakdown, stores fat
- Brain: regulates appetite, body weight, and reward pathways
- Kidneys: influences sodium handling and blood pressure
- Vasculature: dilates blood vessels in healthy state
What Goes Wrong in Diabetes
Type 1 Diabetes
The immune system mistakenly identifies beta cells as foreign and destroys them. By the time symptoms appear, 80 to 90 percent of beta cells are typically already lost. The pancreas can no longer produce enough insulin, so injected insulin is required for life. Read more in our overviews on prediabetes basics.
Type 2 Diabetes and Prediabetes
Insulin resistance develops first — muscle, fat, and liver respond less to insulin. The pancreas compensates by releasing more insulin. For years, beta cells can keep up. Over time, several mechanisms cause decline:
- Glucotoxicity — sustained high glucose damages beta cells directly
- Lipotoxicity — high free fatty acids damage beta cells
- Beta cell exhaustion — sustained overwork leads to dedifferentiation
- Amyloid deposition in islets reduces functional beta cell mass
By type 2 diabetes diagnosis, beta cell function is typically about 50 percent of normal. Without intervention, it continues to decline.
Other Causes of Reduced Insulin Production
- Chronic pancreatitis
- Pancreatic cancer or surgery (pancreatectomy)
- Cystic fibrosis (cystic fibrosis-related diabetes)
- Hemochromatosis (iron overload damaging beta cells)
- Genetic forms of MODY (maturity-onset diabetes of the young)
How Insulin Production Is Measured
| Test | What It Measures | Use |
|---|---|---|
| Fasting C-peptide | Insulin secretion (C-peptide is co-released with insulin) | Distinguishes type 1 from type 2 diabetes |
| Fasting insulin | Direct insulin level | Less common; impacted by injected insulin |
| HOMA-IR | Calculated from fasting glucose and insulin | Estimates insulin resistance |
| Stimulated C-peptide test | Beta cell response to a meal or glucagon | Research and selected clinical scenarios |
| Glucose tolerance test | Glucose response to a 75 g sugar drink | Diagnoses prediabetes and diabetes |
Can You Help Your Pancreas Produce Insulin Better?
For type 2 diabetes and prediabetes, several interventions help preserve and sometimes restore beta cell function:
- Weight loss (5 to 10 percent of body weight) reduces insulin resistance and beta cell stress
- Regular exercise improves muscle glucose uptake and lowers insulin demand
- Lower-carbohydrate or Mediterranean-style diets reduce post-meal glucose surges
- Time-restricted eating gives beta cells rest periods
- Metformin reduces hepatic glucose production, lowering insulin demand
- GLP-1 medications enhance beta cell function and slow decline
- Bariatric surgery can produce remission of type 2 diabetes in some patients
For type 1 diabetes, beta cell preservation is the focus of cutting-edge research (immune therapies, beta cell transplants, encapsulated islet devices). See our overview of treatment options.
Related Reading
For more on the pancreas, glucose regulation, and prediabetes, see our guides on prediabetes basics and treatment options.
The Bottom Line
The pancreas produces insulin in beta cells of the islets of Langerhans. Insulin lowers blood glucose by signaling muscle, fat, and liver to take up glucose from the bloodstream. In type 1 diabetes the beta cells are destroyed; in type 2 and prediabetes the cells initially overproduce insulin to compensate for insulin resistance, then gradually decline. Lifestyle interventions and certain medications can reduce beta cell stress and slow decline in type 2 diabetes. Understanding which problem you have — insulin deficiency or insulin resistance — guides the right treatment plan.
