What Is Amylin? The Forgotten Insulin Partner
Amylin & Pramlintide
100:1 insulin:amylin ratio
Every time your beta cells release insulin, they co-secrete amylin at a ratio of roughly 100:1. The two peptides work together to control post-meal blood sugar.
Hay et al., Pharmacological Reviews, 2015
Hay et al., Pharmacological Reviews, 2015
View as imageEvery time you eat, your pancreatic beta cells release two peptide hormones into your bloodstream: insulin and amylin. Insulin gets the attention. It moves glucose out of the blood and into cells. Amylin does something different. It slows down how fast food leaves your stomach, tells your brain you are full, and stops your liver from dumping extra glucose. For decades, diabetes treatment focused exclusively on replacing insulin while ignoring its partner entirely. That is changing. This article explains what amylin is, what it does, and why it matters for metabolic disease. For clinical applications, see the pillar article on pramlintide, the only approved amylin analog.
Key Takeaways
- Amylin (also called IAPP) is a 37-amino-acid peptide co-secreted with insulin from pancreatic beta cells at a ratio of roughly 100:1[1]
- Amylin slows gastric emptying, suppresses post-meal glucagon secretion, and activates brain satiety circuits in the area postrema and nucleus tractus solitarius[2]
- In type 2 diabetes, amylin misfolds into toxic amyloid fibrils that kill beta cells, creating a self-reinforcing cycle of hormone loss[3]
- Type 1 diabetes patients produce essentially no amylin because their beta cells are destroyed, leaving the hormone completely unreplaced in standard insulin therapy[4]
- Pramlintide, the only FDA-approved amylin analog, reduces HbA1c by 0.3-0.5% and body weight by 1-3 kg when added to insulin[5]
- Next-generation long-acting amylin analogs (cagrilintide, amycretin) are in late-stage clinical trials, combining amylin with GLP-1 activity[6]
The Basics: A 37-Amino-Acid Peptide That Insulin Depends On
Amylin was discovered in 1987 when researchers found amyloid deposits in the pancreatic islets of patients with type 2 diabetes and identified the protein forming those deposits as a novel 37-amino-acid peptide. They called it islet amyloid polypeptide (IAPP). The name "amylin" followed shortly after.[1]
Hay, Chen, and Lutz published a comprehensive pharmacological review in 2015 establishing amylin's core biology.[1] Key facts:
- Amylin is produced exclusively in pancreatic beta cells
- It is stored in the same secretory granules as insulin and released simultaneously in response to meals
- The insulin-to-amylin molar ratio is approximately 100:1 in healthy humans
- Amylin circulates at picomolar concentrations (roughly 4-8 pmol/L fasting, rising to 15-25 pmol/L after meals)
- It signals through the AMY1, AMY2, and AMY3 receptors, which are calcitonin receptors modified by receptor activity-modifying proteins (RAMPs)
The receptor pharmacology is unusual. Bower and Hay described in 2016 how amylin receptors are composite structures: a calcitonin receptor core plus one of three RAMP proteins (RAMP1, RAMP2, or RAMP3) that modify the receptor's ligand preference.[3] This means amylin signaling overlaps with calcitonin signaling, which has implications for bone metabolism and pain pathways.
What Amylin Does: Three Complementary Mechanisms
Slowing Gastric Emptying
Amylin's most potent metabolic effect is slowing the rate at which food moves from the stomach into the small intestine. Lutz documented in a 2025 review that this single mechanism explains much of amylin's effect on post-meal blood sugar: by slowing glucose delivery to the intestine, amylin prevents the rapid glucose spikes that insulin alone cannot handle.[2]
The effect is dose-dependent and mediated through vagal nerve pathways. Amylin activates neurons in the area postrema (a brainstem region outside the blood-brain barrier), which in turn slows gastric motility through vagal efferents to the stomach.
Suppressing Post-Meal Glucagon
After a meal, the liver should stop producing glucose because dietary glucose is now arriving from the gut. Glucagon from pancreatic alpha cells tells the liver to keep producing glucose. Amylin suppresses this inappropriate post-meal glucagon secretion.[4]
In type 1 diabetes, where amylin is absent, post-meal glucagon levels often rise paradoxically, causing glucose to flood in from both dietary absorption and hepatic production simultaneously. This is one reason post-meal glucose control is so difficult with insulin alone.
Activating Satiety Circuits
Hankir and Le Foll mapped the central nervous system pathways targeted by amylin in a 2025 review.[7] Amylin acts on neurons in:
- The area postrema, which detects circulating hormones and initiates meal termination signals
- The nucleus tractus solitarius, which integrates gut-brain communication
- The lateral parabrachial nucleus, which relays satiety information to higher brain centers
- The ventral tegmental area, where amylin modulates the reward value of food
Boyle and Lutz described in 2018 how these pathways give amylin influence over both homeostatic eating (eating to meet energy needs) and hedonic eating (eating for pleasure).[8] This dual influence is part of what makes amylin-based therapies attractive for obesity treatment, a topic explored in detail in why amylin + GLP-1 combinations may be the future of obesity treatment.
Why Amylin Fails in Diabetes
Type 1 Diabetes: Complete Loss
Type 1 diabetes destroys beta cells through autoimmune attack. Since amylin is produced only in beta cells, patients with type 1 diabetes produce essentially zero amylin. Standard insulin therapy replaces one hormone but not the other. Volcansek and colleagues noted in a 2025 review that this creates a "dual hormone deficiency" that helps explain why glucose control remains difficult in type 1 diabetes even with advanced insulin delivery systems.[9]
Type 2 Diabetes: Misfolding and Toxicity
In type 2 diabetes, the problem is different. Beta cells initially overproduce both insulin and amylin in response to insulin resistance. At high concentrations, human amylin misfolds and aggregates into amyloid fibrils. These fibrils are cytotoxic to beta cells.[3]
This creates a destructive cycle: insulin resistance forces beta cells to produce more amylin, the excess amylin forms toxic aggregates, the aggregates kill beta cells, and the remaining beta cells must compensate by producing even more. Over time, this process contributes to the progressive beta cell failure that characterizes advanced type 2 diabetes.
Chung and Kim described in a 2026 review how amyloid deposits are found in the islets of roughly 90% of patients with type 2 diabetes at autopsy.[10] The deposits correlate with disease severity and duration, though whether they cause beta cell death or are a marker of it remains debated.
Notably, rodent amylin does not form amyloid. Proline residues at positions 25, 28, and 29 in rat and mouse amylin prevent the misfolding that occurs in the human sequence. This species difference is why pramlintide was engineered with three proline substitutions at these positions to create a soluble, non-aggregating version of human amylin.
Beyond Blood Sugar: Amylin's Broader Biology
Amylin and Alzheimer's Disease
Amylin's tendency to form amyloid aggregates connects it to Alzheimer's disease research. Amylin aggregates have been found in the brains of patients with type 2 diabetes, and the amyloid-forming mechanism shares structural similarities with amyloid-beta aggregation in Alzheimer's. Paradoxically, some evidence suggests that non-aggregated amylin (or pramlintide) may have neuroprotective effects by competing with amyloid-beta for binding sites or by activating protective signaling pathways.[11]
Amylin and Cardiovascular Risk
Koshy and Fernandez reviewed the cardiovascular safety profile of amylin analogs in 2021, finding no increased cardiovascular risk and some signals suggesting cardiovascular benefit, including improvements in lipid profiles and inflammatory markers.[5] However, dedicated cardiovascular outcome trials for amylin analogs have not been completed.
The Current Drug Landscape
Pramlintide: First Generation
Pramlintide (Symlin), approved by the FDA in 2005, is a synthetic analog of human amylin with three proline substitutions that prevent aggregation. It is injected before meals alongside insulin and reduces post-meal glucose excursions, HbA1c, and body weight. For a detailed analysis of pramlintide's clinical history and limitations, see pramlintide: the only approved amylin analog.
Cagrilintide: Long-Acting Next Generation
Kruse and colleagues described the development of cagrilintide in 2021, a long-acting amylin analog designed for once-weekly injection.[6] Unlike pramlintide (which requires injection before each meal), cagrilintide uses acylation technology to extend its half-life. When combined with semaglutide (a GLP-1 agonist) as CagriSema, the dual-hormone approach produced weight loss exceeding what either drug achieved alone. For details on cagrilintide specifically, see cagrilintide: amylin reimagined for the GLP-1 era. For GLP-1 drug background, see the history of GLP-1 drugs.
Emerging Approaches
Lee reviewed the expanding pipeline of amylin receptor activators in 2025, documenting multiple candidates beyond cagrilintide that target different receptor subtypes or combine amylin activity with other incretin pathways.[12] Rejili and colleagues separately reviewed amylin receptors as therapeutic targets for obesity, noting that receptor subtype selectivity may allow different clinical profiles (more satiety vs. more gastric slowing vs. more glucagon suppression).[13]
Walker and colleagues characterized the emerging therapeutic opportunities for amylin in a 2025 review, emphasizing that the combination of amylin with GLP-1 receptor agonism represents a potential step change in obesity and diabetes management.[14]
How Amylin and GLP-1 Differ and Complement Each Other
Amylin and GLP-1 are often discussed together because both slow gastric emptying and reduce appetite. But they work through fundamentally different biology.
GLP-1 is an incretin hormone produced by L-cells in the gut wall in response to nutrients. Its primary metabolic function is enhancing glucose-dependent insulin secretion from beta cells. GLP-1 also suppresses glucagon secretion and slows gastric emptying, but it does these things through different receptors and neural pathways than amylin.[9]
Amylin is not an incretin. It does not enhance insulin secretion. Instead, it modulates the post-meal glucose response by controlling the rate at which glucose appears in the blood (via gastric emptying) and the rate at which the liver adds more (via glucagon suppression). Where GLP-1 increases insulin output, amylin reduces the demand for insulin in the first place.
This complementarity is why combining the two pathways produces additive or synergistic effects. Volcansek and colleagues noted that amylin acts primarily through brainstem circuits while GLP-1 engages both brainstem and hypothalamic pathways, activating partially overlapping but distinct satiety networks.[9] Blocking one pathway does not fully compensate for the other, which explains why adding amylin activity to GLP-1 therapy produces weight loss beyond the GLP-1 ceiling.
What Remains Uncertain
The biology of amylin is well-established. What remains less clear is how much of diabetes and obesity treatment will ultimately incorporate amylin-based therapies alongside the GLP-1 drugs that currently dominate the landscape. CagriSema clinical data suggests the combination is more effective than either component alone, but long-term safety data, cost, and comparative effectiveness studies are still accumulating.
The Alzheimer's connection is intriguing but unresolved. Whether amylin agonism or antagonism would benefit neurodegenerative disease patients is a question that preclinical data has not settled. Clinical trials would be needed to determine the direction of effect.
The relationship between amylin amyloid formation and beta cell death in type 2 diabetes is correlational in human studies. The causal direction is supported by cell culture and animal data but has not been definitively established in humans.
The Bottom Line
Amylin is a 37-amino-acid peptide co-secreted with insulin that controls post-meal blood sugar through three complementary mechanisms: slowing gastric emptying, suppressing glucagon, and signaling satiety to the brain. It is deficient in both type 1 (complete loss) and type 2 diabetes (misfolding and toxicity). Pramlintide is the only approved amylin replacement, but long-acting analogs like cagrilintide, especially combined with GLP-1 agonists, are in late-stage development and may represent the next frontier in metabolic disease treatment.