Islet amyloid polypeptide (IAPP), or amylin, is a hormone made by pancreatic beta cells. Learn how IAPP misfolding links to type 2 diabetes and beta-cell loss.
Islet amyloid polypeptide (IAPP), also called amylin, is a 37-amino-acid hormone made and released by the beta cells of the pancreas. It is packaged and secreted alongside insulin and helps regulate blood sugar, slow stomach emptying, and signal fullness after a meal. In type 2 diabetes, IAPP can misfold and clump into amyloid deposits inside the pancreatic islets, and that buildup is associated with beta-cell damage.
What Is Islet Amyloid Polypeptide Made Of?
IAPP's polypeptide structure is short — just 37 amino acids — but it has an unusual feature. A central stretch of the molecule readily shifts into a beta-sheet shape, and beta sheets stack neatly, which is exactly what makes IAPP prone to forming fibers.
The human sequence, often written hIAPP, differs from the rodent version by a few amino acids. Rats and mice make an IAPP that aggregates far less readily, which is one reason animal models never perfectly mirror human type 2 diabetes.
IAPP belongs to the calcitonin family of peptides, alongside calcitonin gene-related peptide and adrenomedullin. Among the polypeptide names you see in endocrinology, amylin stands out because it has a dual identity: a normal hormone and a protein capable of misfolding.
What Does IAPP Do in a Healthy Body?
IAPP acts as a partner to insulin. When blood glucose rises, beta cells release both hormones together in a roughly fixed ratio. IAPP then does several jobs at once:
- Slows gastric emptying, so food stays in the stomach longer and glucose enters the bloodstream more gradually.
- Promotes satiety by acting on receptors in the area postrema of the brainstem.
- Suppresses glucagon release from alpha cells, trimming extra glucose output from the liver.
- Modestly reduces glucose production and appears to support insulin's action in muscle.
Together, these effects smooth out post-meal glucose spikes. One of the clearest polypeptide examples of hormone teamwork is the insulin-amylin pair: both come from the same vesicle, and both help the body handle a meal.
IAPP and Type 2 Diabetes: The Amyloid Connection
Islet amyloid polypeptide and type 2 diabetes are closely linked because of what happens when IAPP is overproduced. In insulin resistance, beta cells compensate by making more insulin — and more IAPP. As IAPP concentrations climb, the peptide can misfold, assemble into small oligomers, and eventually form amyloid fibrils.
Pathologists have found islet amyloid in the large majority of pancreases from people with type 2 diabetes, while it is uncommon in people without the disease. The deposits sit between beta cells and are associated with reduced beta-cell mass and weaker insulin secretion.
Precision matters here. IAPP aggregation is widely viewed as a contributing factor to beta-cell failure, not the sole cause of type 2 diabetes. Genetics, insulin resistance, low-grade inflammation, and lipotoxicity all play roles.
Research suggests that soluble IAPP oligomers, rather than mature amyloid fibers, may be the most toxic species to beta cells.
IAPP vs Other Pancreatic and Gut Hormones
IAPP is often confused with other peptides produced in or near the pancreas. The table below separates them by source and function.
| Hormone | Producing cell | Main role |
|---|---|---|
| IAPP (amylin) | Pancreatic beta cells | Slows gastric emptying, promotes satiety, works with insulin |
| Insulin | Pancreatic beta cells | Moves glucose into muscle and fat cells |
| Glucagon | Pancreatic alpha cells | Raises blood glucose between meals |
| Pancreatic polypeptide | PP cells (F cells) | Regulates pancreatic exocrine secretion and satiety |
| Somatostatin | Delta cells | Paracrine brake on other islet hormones |
Pancreatic polypeptide is a different hormone entirely. It comes from distinct cells and is sometimes measured clinically as a marker in neuroendocrine tumors. It shares the "polypeptide" label but not IAPP's tendency to form amyloid.
How IAPP Is Cleared, Studied, and Targeted
Like other small peptides, IAPP is broken down by proteases. Polypeptide hydrolysis by insulin-degrading enzyme and related peptidases normally keeps amyloid-prone fragments in check. When clearance falls behind production, aggregation becomes more likely.
Researchers investigate IAPP with several tools:
- Thioflavin T and Congo red staining to detect amyloid in tissue samples.
- Solid-state NMR and cryo-electron microscopy to map fibril structure at atomic resolution.
- Transgenic mouse models that express human IAPP.
- Human islet studies from organ donors with and without type 2 diabetes.
Is there a drug that targets IAPP?
Pramlintide (brand name Symlin) is a synthetic amylin analog approved by the FDA as an adjunct to insulin for adults with type 1 or type 2 diabetes. It is not IAPP itself. Three amino acids are swapped so the molecule will not aggregate, but it still activates the same receptors.
Pramlintide is injected at meals and can improve post-meal glucose control and support modest weight loss. It also carries a boxed warning for severe hypoglycemia, particularly when insulin doses are not adjusted.
Experimental strategies include stabilizing IAPP to prevent misfolding, blocking aggregation with small molecules, and using antibodies to clear oligomers. None of these approaches is approved for routine clinical use.
What This Means for Patients
If you have type 2 diabetes or prediabetes, IAPP biology is one more reason to focus on treatments that reduce the workload on beta cells. Weight loss, glucose-lowering medication, and early glycemic control all lower the demand for insulin and IAPP production.
IAPP is not measured in routine blood tests, and no approved therapy directly clears islet amyloid. Talk with a healthcare professional before changing any diabetes medication, and never adjust insulin or pramlintide on your own.
Cosmetic peptides sold in skincare are unrelated to IAPP. Topical peptide products work on the surface of the skin, while islet amyloid polypeptide is an internal metabolic hormone studied in diabetes research.
Frequently Asked Questions
Is islet amyloid polypeptide the same as amylin?
Yes. IAPP and amylin are two names for the same 37-amino-acid hormone produced by pancreatic beta cells. "Amylin" is usually used when describing its role as a hormone, while "islet amyloid polypeptide" is used when discussing the amyloid deposits found in type 2 diabetes.
Does islet amyloid polypeptide cause type 2 diabetes?
No. IAPP does not cause type 2 diabetes on its own. It is a normal hormone made with insulin, and its aggregation into islet amyloid is considered one contributing factor to beta-cell dysfunction alongside insulin resistance, genetics, and inflammation.
Is pramlintide the same thing as IAPP?
No. Pramlintide is a synthetic analog of human amylin with three amino acid substitutions that keep it from forming amyloid. It is FDA-approved as an injectable adjunct to insulin for adults with type 1 or type 2 diabetes.
This page provides educational research information and does not replace medical advice, diagnosis, or treatment.