Incretin & satiety signaling
One of 4 mechanistic pathways to 📉 Metabolic health & insulin sensitivity · 19 options
GLP-1 and GIP are released by the gut in response to food. They amplify glucose-dependent insulin secretion — meaning they raise insulin only when glucose is high, which is why they don't cause hypoglycemia the way sulfonylureas do.
The monitoring panel for anyone on a GLP-1. Lipase and amylase are there for the pancreatitis signal, and thyroid because of the medullary carcinoma contraindication — both are on the label and rarely tracked.
HbA1c (Hemoglobin A1c)Fasting InsulinC-Peptide, SerumLipaseAmylaseComprehensive Metabolic Panel (CMP)TSH (Thyroid-Stimulating Hormone)💉 On a GLP-1 (Semaglutide / Tirzepatide) covers these in one panel →
What engages this pathway
Ordered by how directly each one acts on the mechanism above — never by how much trial evidence exists. Each links to its full breakdown with dosing, half-life and vendor.
💉 Semaglutide
GLP-1 agonism improves HbA1c substantially and has cardiovascular outcome data in SELECT and SUSTAIN-6 — benefit beyond glucose control.
💉 Tirzepatide
Dual GIP/GLP-1 with the strongest glycemic and weight results in head-to-head trials.
💉 Retatrutide
Triple agonism adding glucagon-mediated hepatic fat oxidation — particularly relevant to fatty liver.
💉 UBT251
A GLP-1/GIP/glucagon triple agonist built on the same three-receptor logic as Retatrutide. On glycemic control the expectation is the class effect; the glucagon arm is the part to watch, since glucagon raises hepatic glucose output as well as expenditure. Early human data, and far less of it than anything above.
💉 Survodutide
GLP-1/glucagon dual with hepatic fat reduction as a specific target.
💉 Pemvidutide
Tuned deliberately toward liver fat and lean-mass preservation.
💉 Mazdutide
GLP-1/glucagon dual with substantial Chinese trial data.
💉 Orforglipron
Oral non-peptide GLP-1 — same mechanism, no injection.
💉 Ecnoglutide
Long-acting GLP-1 with a cAMP-biased signaling profile.
💉 Dulaglutide
Weekly GLP-1 with cardiovascular outcome data in REWIND.
💉 Liraglutide
Daily GLP-1 with the LEADER outcome trial behind it.
💉 Exenatide
The first-generation GLP-1, derived from Gila monster venom. Mechanistically identical to the modern agents and clinically outclassed by them on both dosing and effect size.
💉 Amycretin
GLP-1 plus amylin in one molecule; early human data is promising.
💉 Pramlintide
Amylin analog that slows gastric emptying and suppresses inappropriate post-meal glucagon — an underused mechanism.
💉 Cagrilintide
Long-acting amylin analog, usually paired with a GLP-1.
💉 Eloralintide
Selective amylin receptor agonist aiming for satiety with less nausea.
🧬 GLP-1 Support Stack
Covers the muscle-loss, constipation and micronutrient issues that come with incretin therapy.
🧬 Fiber (FiberMend)
Fermentable fiber raises endogenous GLP-1 through colonic short-chain fatty acid production — the physiological version of the same pathway.
🧬 Partially Hydrolysed Guar Gum (PHGG)
Viscous fiber that slows gastric emptying without the fermentation load.
What actually decides this outcome, in order of size
This is prescription pharmacology and the questions that decide the outcome are clinical ones. Ranked by how much of the outcome each one owns:
- Whether insulin secretion is glucose-dependent, which is the property this whole class is built on. These receptors amplify insulin release when glucose is high and stop amplifying it when glucose is not, and the physiology has been reviewed in detail Drucker 2022. That dependence is why the class does not produce hypoglycemia the way a sulfonylurea does, and it is also why adding one to insulin changes the calculation entirely.
- Who is prescribing and who is monitoring. Defined contraindications, a pancreatitis and gallbladder signal, thyroid C-cell labeling for several agents, and anesthetic implications from delayed gastric emptying. The safety profile has been reported from a large randomized trial Kushner 2025, and the oversight is part of the intervention rather than a formality around it.
- Which receptors the molecule actually engages, because the class name hides the differences. A GLP-1 agonist, a dual GIP and GLP-1 agonist, a triple agonist adding glucagon Jastreboff 2023, an oral non-peptide agonist Horn 2025 and a selective amylin receptor agonist Billings 2025 are five different pharmacologies sharing a shelf. Combination products behave differently again Buse 2026.
- What the outcome data attaches to, which is not the glucose number. In a large cardiovascular outcomes trial the benefit was examined by baseline glycated hemoglobin and by change in it, and it was not explained by either Lingvay 2024. Kidney outcomes were reported separately from the same program Colhoun 2024. That is the clearest statement available anywhere on this site that a surrogate moving and an outcome moving are two different findings.
- What the agent does to everything else you swallow. Delayed gastric emptying is part of the mechanism Drucker 2022, and amylin agonism delays it further Boyle 2022. The prediction, and it is an extrapolation from the mechanism rather than a trial result, is that oral drugs with narrow absorption windows are the ones to review with a pharmacist, including oral contraceptives.
- What comes off besides fat, which is measurable and is part of the trade. A myostatin-pathway antibody was combined with an incretin agonist in a randomized trial specifically because lean mass is part of what is lost Heymsfield 2026, which is why resistance training belongs beside the prescription rather than after it.
The order to run these in, and what has to be true first
Clinical assessment, baseline bloods, one agent, monitoring on a schedule. Nothing on this page is a self-directed purchase, and the sequence assumes a prescriber throughout.
- The clinical conversation this page cannot have. Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, pancreatitis, gallstones, gastroparesis, retinopathy, pregnancy or planned pregnancy, and the full medication list. Any one of these changes the answer, and the safety reporting from the large trials is what those conversations draw on Kushner 2025.
- Baseline bloods on one requisition. HbA1c (Hemoglobin A1c) with Comprehensive Metabolic Panel (CMP), Lipid Panel (Cholesterol, HDL, LDL, Triglycerides) with ApoB (Apolipoprotein B), C-Peptide, Serum with Fasting Insulin, and Amylase with Lipase so that a later abdominal pain has something to be compared against. Calcitonin is not a screening test for this indication and should not be ordered as one.
- C-peptide before anything if the diabetes type is not certain. This class has been examined as adjunctive therapy in type 1 diabetes Avgerinos 2021, which is a different clinical situation with a different risk profile, and C-Peptide, Serum is the cheap test that separates them.
- Semaglutide or Tirzepatide first among the injectables, because they carry the largest randomized outcome files Lingvay 2024 Colhoun 2024. Titration is slow for a reason: the gastrointestinal effects are dose-related and are the commonest cause of stopping.
- Orforglipron and Ecnoglutide are the oral and biased-agonist versions of the same receptor. An oral non-peptide agonist has phase 3 data Horn 2025, and the practical difference is exposure profile and administration rather than mechanism.
- Retatrutide, Survodutide, Mazdutide, Pemvidutide and UBT251 add glucagon or GIP activity. Retatrutide's phase 2 results are published Jastreboff 2023; a glucagon component raises energy expenditure and hepatic glucose output at the same time, which raises the monitoring burden rather than only the effect.
- Pramlintide, Cagrilintide, Eloralintide and Amycretin are the amylin arm and a different receptor family. Amylin's role in metabolic control has been reviewed Boyle 2022, chronic pramlintide reduced feeding through a reduction in meal size in a preclinical model Kern 2024, a selective agonist has phase 1 data Billings 2025, and the combination with a GLP-1 agonist has its own randomized evidence Buse 2026.
- Fiber (FiberMend) and Partially Hydrolysed Guar Gum (PHGG) are the endogenous version of the same pathway and are not in the same units. Fermentable fiber raises the body's own incretin output through colonic short-chain fatty acid production; viscous fiber slows gastric emptying mechanically. Fermentation and gas production interact, which is the practical tolerability question Alhasani 2024.
What gets bought for this that cannot move it
The category that fails structurally is the fiber arm sold beside the pharmacology as though they were alternatives. A viscous fiber changes gastric volume and transit mechanically; a receptor agonist engages a signaling system centrally and peripherally Drucker 2022. Both reduce intake and the effect sizes are not remotely comparable. Putting them on one list invites a reader to substitute the cheap one for the expensive one and conclude the mechanism does not work.
The surrogate on this page is glycated hemoglobin, and the strongest evidence here is that it is not the mechanism of benefit. The cardiovascular outcome was analyzed by baseline glycated hemoglobin and by change in it and was explained by neither Lingvay 2024. So a flat glucose number is not evidence the drug is failing, and a falling one is not proof it is working through the route that matters. This is the single clearest example on the site of a surrogate and an outcome coming apart, and it points in the direction people do not expect.
Two clinical failures that are specific to this class. Nausea suppresses intake independently of the receptor, so a tolerability problem can look like efficacy Drucker 2022. And heart rate rises modestly across this class, which has been quantified in systematic review Robinson 2013; it is usually unimportant and it is not nothing, which is why the baseline observation is worth having.
If the goal underneath is different, so is the page. If the target is the post-meal curve rather than the average, Glucose disposal, absorption & the post-meal curve. If it is hepatic fat, Hepatic fat & fatty liver. If it is body composition, Appetite & satiety signaling is the page written for that question and Lean-mass protection while cutting is the one that addresses what comes off with the fat Heymsfield 2026. If eating is a source of distress rather than a quantity problem, this pharmacology is the wrong instrument and the right step is a clinician who works with eating. And severe or persistent abdominal pain on any agent in this class is an urgent assessment, not a dose adjustment.
How you would know it was working, on a real read-out and a real timescale
This page makes two predictions. HbA1c (Hemoglobin A1c) moves within twelve weeks on an effective agent at an effective exposure, and the size of that move will not tell you what the drug is doing to your arteries Lingvay 2024; and C-Peptide, Serum measured once at the beginning will change the plan for a minority of readers, because it identifies the ones for whom this class is adjunctive rather than primary Avgerinos 2021.
- HbA1c (Hemoglobin A1c) at baseline and 12 weeks. Twelve weeks because glycated hemoglobin integrates over the circulating red cell population, so an eight-week draw reports the titration rather than the dose.
- C-Peptide, Serum with Fasting Insulin once at baseline. This pair says how much endogenous secretion there is to amplify, which is the mechanistic precondition for the entire class Drucker 2022.
- Amylase and Lipase at baseline, and repeated only if abdominal pain appears. They exist here as a comparison value. Ordering them monthly in an asymptomatic person generates false alarms rather than safety Kushner 2025.
- Comprehensive Metabolic Panel (CMP) and Lipid Panel (Cholesterol, HDL, LDL, Triglycerides) with ApoB (Apolipoprotein B) at baseline and 6 months. Renal function matters if vomiting or diarrhea occurs, and kidney outcomes were reported as their own analysis in this program Colhoun 2024.
- Resting heart rate, weekly, at the same time of day. The class raises it modestly and the size has been quantified in systematic review Robinson 2013. This is free and nobody records it.
What will fool you. Glycated hemoglobin is unreliable in anything that changes red cell lifespan, so anemia or recent blood loss will move it without any change in glucose. Nausea reduces intake and improves every metabolic number for a reason unrelated to the receptor Drucker 2022. Delayed gastric emptying changes the absorption of anything taken with these agents Boyle 2022, which matters for oral drugs with narrow windows. A dose held at the starting titration step is not the dose the trials used, so a null result may be an exposure result. And an unlicensed vial of any of these has no assay behind it: the dose written on it is a claim.
Sources read for these sections
- Drucker DJ. GLP-1 physiology informs the pharmacotherapy of obesity. Molecular Metabolism 2022 · PMID 34626851
- Lingvay I. Semaglutide and Cardiovascular Outcomes by Baseline HbA1c and Change in HbA1c in People With Overweight or Obesity but Without Diabetes in SELECT. Diabetes Care 2024 · PMID 38907684
- Colhoun HM, et al. Long-term kidney outcomes of semaglutide in obesity and cardiovascular disease in the SELECT trial. Nature Medicine 2024 · PMID 38796653
- Kushner RF, et al. Safety profile of semaglutide versus placebo in the SELECT study: a randomized controlled trial. Obesity (Silver Spring) 2025 · PMID 39948761
- Robinson LE, Holt TA, Rees K. Effects of exenatide and liraglutide on heart rate, blood pressure and body weight: systematic review and meta-analysis.. BMJ Open 2013 · PMID 23355666
- Avgerinos I, et al. Comparative efficacy and safety of glucose-lowering drugs as adjunctive therapy for adults with type 1 diabetes: A systematic review and network meta-analysis. Diabetes, Obesity and Metabolism 2021 · PMID 33300282
- Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. New England Journal of Medicine 2023 · PMID 37366315
- Horn DB, et al. Orforglipron, an oral small-molecule GLP-1 receptor agonist, for the treatment of obesity in people with type 2 diabetes (ATTAIN-2): a phase 3, double-blind, randomised, multicentre, placebo-controlled trial. The Lancet 2025 · PMID 41275875
- Boyle CN, Le Foll C, Lutz TA. Mediators of Amylin Action in Metabolic Control. Journal of Clinical Medicine 2022 · PMID 35456307
- Kern KA, et al. Chronic pramlintide decreases feeding via a reduction in meal size in male rats. Peptides 2024 · PMID 38493922
- Billings LK, et al. Eloralintide, a selective amylin receptor agonist for the treatment of obesity: a 48-week phase 2, multicentre, double-blind, randomised, placebo-controlled trial. Lancet 2025 · PMID 41207310
- Buse JB, et al. Cagrilintide-semaglutide (CagriSema) versus semaglutide or cagrilintide in people with type 2 diabetes (REIMAGINE 2): a double-blind, randomised, controlled, phase 3 study. The Lancet Diabetes & Endocrinology 2026 · PMID 42251859
- Heymsfield SB, et al. Bimagrumab plus semaglutide alone or in combination for the treatment of obesity: a randomized phase 2 trial. Nature Medicine 2026 · PMID 41772149
- Alhasani AT. Mode of Action of Psyllium in Reducing Gas Production from Inulin and its Interaction with Colonic Microbiota: A 24-hour, Randomized, Placebo-Controlled Trial in Healthy Human Volunteers. J Nutr 2024 · PMID 39732438
The other 3 routes to metabolic health & insulin sensitivity
Pick the pathway that matches where you are actually stuck. An appetite drug does nothing for someone who already undereats.
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This pathway is one arm of The Metabolic health & insulin sensitivity Blueprint. The members' version has where this arm sits in the sequence, what to stack it with, and the markers that tell you to keep going or stop.
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Frequently asked questions
GLP-1 and GIP are released by the gut in response to food. They amplify glucose-dependent insulin secretion — meaning they raise insulin only when glucose is high, which is why they don't cause hypoglycemia the way sulfonylureas do.
19 options are mapped to this pathway in the Vault, including Semaglutide, Tirzepatide, Retatrutide, UBT251. They are grouped by the mechanism they act through rather than ranked by how much trial evidence exists — 15 carry clinical validation and 4 are mechanistic predictions.
The monitoring panel for anyone on a GLP-1. Lipase and amylase are there for the pancreatitis signal, and thyroid because of the medullary carcinoma contraindication — both are on the label and rarely tracked. The markers worth checking are HbA1c (Hemoglobin A1c), Fasting Insulin, C-Peptide, Serum, Lipase.
Unproven is not the same as ineffective. Of the 19 options on this pathway, 15 have clinical validation and 4 are graded theoretical — meaning the mechanism is sound but the specific human trial has not been run, which is true of a great deal of what works in this space. Nothing on this page is ordered by evidence tier, because sorting by trial count would bury the compounds you came looking for.
Where this goes next
Everything above is the free case for Incretin & satiety signaling. The protocol — the dosing, the order to correct things in, the week-by-week schedule and what to retest — is a lesson inside Skool.