GLP-1 Glossary

Once-weekly injectable semaglutide approved by the FDA in 2021 for chronic weight management. Same active ingredient as Ozempic but at higher doses (0.25 to 2.4 mg weekly).

View term page →Wegovy in our brand-comparison piece →

Once-weekly injectable semaglutide FDA-approved for type 2 diabetes (0.5, 1, 2 mg). Same molecule as Wegovy but lower target doses; commonly prescribed off-label for weight loss.

View term page →Ozempic drug page →

Oral semaglutide tablets (3, 7, 14 mg daily) FDA-approved for type 2 diabetes. The pivotal pharmacokinetic source for the 33% levothyroxine AUC interaction warning.

View term page →GLP-1 + levothyroxine deep dive →

Once-daily injectable liraglutide 3.0 mg, FDA-approved 2014 for chronic weight management. Shorter half-life (~13 hours) than the once-weekly GLP-1s requires daily dosing.

View term page →GLP-1 side effects investigation →

Once-weekly injectable tirzepatide FDA-approved 2023 for chronic weight management. Dual GLP-1/GIP receptor agonist; produced ~21% body weight reduction at 15 mg in SURMOUNT-1.

View term page →Tirzepatide vs semaglutide head-to-head →

Once-weekly injectable tirzepatide FDA-approved 2022 for type 2 diabetes. Same molecule as Zepbound. Carries the same 4-week backup-contraception warning on oral hormonal contraceptives.

View term page →Mounjaro/Zepbound + birth control →

Orforglipron tablets, the first oral non-peptide GLP-1 receptor agonist, FDA-approved April 2026 by Eli Lilly. Daily oral dosing on empty stomach with a 30-minute fast window.

View term page →How to take Foundayo (orforglipron) →

Generic name for the active ingredient in Wegovy, Ozempic, and Rybelsus. GLP-1 receptor agonist with ~7-day half-life enabling once-weekly subcutaneous dosing.

View term page →Semaglutide drug page →

Generic name for the active ingredient in Mounjaro and Zepbound. Dual GLP-1 and GIP receptor agonist with ~5-day half-life. The only injectable GLP-1 with an FDA-mandated oral contraceptive interaction warning.

View term page →Tirzepatide drug page →

Generic name for Foundayo. The first oral non-peptide GLP-1 receptor agonist. Different mechanism for the oral-contraceptive warning (co-localization in the GI tract) vs tirzepatide's gastric-emptying delay.

View term page →What is orforglipron / Foundayo →

Eli Lilly's investigational triple agonist (LY3437943) targeting GLP-1, GIP, and glucagon receptors. Phase 2 (NEJM 2023, Jastreboff et al.) showed up to 24.2% body weight reduction at 48 weeks at the highest dose. The first phase 3 readout, TRIUMPH-4 (Dec 2025), reported 28.7% mean weight loss in adults with obesity and knee osteoarthritis. Not yet FDA-approved.

View term page →Retatrutide: Lilly's triple agonist evidence →

Novo Nordisk's investigational fixed-dose combination of cagrilintide (long-acting amylin analog) plus semaglutide (GLP-1 agonist). REDEFINE 1 reported 20.4% mean weight loss at 68 weeks (22.7% adherent estimand) versus 14.9% with semaglutide alone. Novo has filed an NDA. The result missed Novo's 25% guidance benchmark but still beat semaglutide monotherapy.

View term page →CagriSema REDEFINE trial results →

Novo Nordisk's long-acting amylin analog. Studied alone (11.5% weight loss at 68 weeks in REDEFINE 1) and as the amylin component of CagriSema combined with semaglutide. Distinct mechanism from GLP-1 agonists — works on amylin receptors that signal satiety via the brainstem.

View term page →CagriSema REDEFINE trial results →

Boehringer Ingelheim and Zealand Pharma's investigational dual agonist of GLP-1 and glucagon receptors. Phase 2 reported up to 19% weight loss at 46 weeks. The phase 3 SYNCHRONIZE program is enrolled; not yet FDA-approved.

View term page →GLP-1 pipeline: survodutide, MariTide, ecnoglutide →

Amgen's investigational once-monthly conjugate combining a GLP-1 receptor agonist with a GIP receptor antagonist. Phase 2 (NEJM 2025) reported 16-20% weight loss. The mechanism is unique: opposite GIP direction versus tirzepatide (which is a GIP agonist). Not yet FDA-approved.

View term page →GLP-1 pipeline: survodutide, MariTide, ecnoglutide →

Sciwind Biosciences' biased GLP-1 receptor agonist (licensed to Pfizer for China). Phase 3 SLIMMER trial reported positive results in Lancet Diabetes Endocrinology 2025. Approved by China's NMPA. Not FDA-approved and not in active US development.

View term page →GLP-1 pipeline: survodutide, MariTide, ecnoglutide →

A daily-injection GLP-1 receptor agonist marketed as Victoza (for type 2 diabetes, 1.2 / 1.8 mg) and Saxenda (for chronic weight management, 3.0 mg). Daily subcutaneous administration distinguishes it from the weekly GLP-1s. Elimination half-life ~13 hours. The LEADER trial established its cardiovascular benefit in T2D.

View term page →Saxenda drug page →

A GLP-1 receptor agonist available as twice-daily Byetta and once-weekly Bydureon (extended-release). First GLP-1 approved by the FDA in 2005 for type 2 diabetes. The EXSCEL trial showed neutral CV outcomes — distinguishing exenatide from semaglutide / liraglutide / dulaglutide which all showed CV benefit.

View term page →EXSCEL trial →

A once-weekly GLP-1 receptor agonist marketed as Trulicity for type 2 diabetes (0.75 / 1.5 / 3.0 / 4.5 mg). The REWIND trial established cardiovascular benefit in a majority primary-prevention population. NOT FDA-approved for chronic weight management; off-label weight-loss effect is modest (~3-6% TBWL).

View term page →Trulicity drug page →

A once-weekly GLP-1 receptor agonist marketed as Tanzeum by GSK. Approved by the FDA in 2014 for type 2 diabetes; withdrawn from global markets by GSK in 2017 due to low commercial uptake. The HARMONY OUTCOMES trial (Lancet 2018) demonstrated 22% MACE reduction — published after withdrawal.

View term page →HARMONY OUTCOMES trial →

An oral fixed-dose combination of naltrexone 8 mg + bupropion 90 mg ER, taken twice daily after a 4-week titration. FDA-approved September 2014 for chronic weight management. Pivotal trial (COR-I) showed -6.1% body weight at 56 weeks. Carries a boxed warning for suicidal behavior in young adults due to the bupropion component.

View term page →Contrave drug page →

An oral once-daily combination of phentermine + topiramate extended-release at four dose strengths (3.75/23 to 15/92 mg). FDA-approved July 2012 for chronic weight management. EQUIP trial showed -10.9% body weight at 56 weeks. Requires a REMS contraception program due to topiramate teratogenicity risk.

View term page →Qsymia drug page →

A dopamine and norepinephrine reuptake inhibitor used as an antidepressant (Wellbutrin), smoking-cessation aid (Zyban), and the active half of Contrave. Modest single-agent weight-loss effect (~2-3 kg). Carries a boxed warning for suicidal behavior in young adults. Contraindicated in seizure disorders and active eating disorders.

View term page →Bupropion weight-loss evidence review →

An opioid receptor antagonist used at 50 mg daily for alcohol and opioid use disorder, and at low dose (1.5-4.5 mg, off-label) for various inflammatory conditions. The 8 mg component of Contrave contributes to appetite + reward-pathway modulation when paired with bupropion. Single-agent weight-loss effect is minimal.

View term page →Naltrexone and Contrave evidence review →

A sympathomimetic appetite suppressant approved by the FDA in 1959 for short-term (≤12 weeks) weight management. The most widely prescribed weight-loss medication in the US historically. Single-agent dosing 8-37.5 mg daily. The phentermine half of Qsymia. Schedule IV controlled substance; cardiovascular contraindications apply.

View term page →Phentermine vs Ozempic comparison →

An antiepileptic medication with FDA approval for seizure disorders and migraine prophylaxis. Also produces modest single-agent weight loss (~3-4 kg) and is the extended-release half of Qsymia. Side effects include paresthesias, taste alteration, cognitive slowing. Teratogenic — requires REMS contraception program when used in Qsymia for weight management.

View term page →Topiramate and Qsymia weight-loss review →

An investigational GLP-1 + glucagon dual receptor agonist developed by Altimmune. The dual-mechanism design targets both appetite suppression (GLP-1) and increased energy expenditure (glucagon). Currently in phase 2/3 trials for obesity and MASH. Not FDA-approved.

View term page →GLP-1 pipeline tracker →

An investigational GLP-1 + glucagon dual receptor agonist developed by Innovent Biologics, marketed in China as 信尔达 (Xinerda). Approved by China's NMPA in March 2025 for chronic weight management. Not FDA-approved or available in the United States.

View term page →GLP-1 pipeline tracker →

G-protein coupled receptor that responds to glucagon-like peptide-1. Activation by GLP-1 medications suppresses appetite, slows gastric emptying, and improves glucose-dependent insulin secretion.

View term page →How long does GLP-1 take to work →

Glucose-dependent insulinotropic polypeptide receptor. Tirzepatide is a dual agonist of both GLP-1 and GIP receptors, which is the proposed basis for its larger gastric-emptying delay than the semaglutides.

View term page →Tirzepatide vs semaglutide head-to-head →

A medication that activates two receptors at once. Tirzepatide is the GLP-1/GIP dual agonist currently on the market; CagriSema (cagrilintide + semaglutide) and survodutide (GLP-1/glucagon) are in late-stage trials.

View term page →GLP-1 pipeline: survodutide, maridebart, ecnoglutide →

The rate at which food and oral medications leave the stomach. GLP-1 medications slow gastric emptying — the same mechanism that produces appetite suppression also drives the oral-contraceptive and levothyroxine drug interactions.

View term page →GLP-1 nausea management guide →

Patient term for persistent intrusive thoughts about food and eating. Most patients on GLP-1s report food noise reducing within the first 4-8 weeks. Not a formal medical term but widely reported in cohort studies.

View term page →GLP-1 side-effect questions answered →

A peptide that activates three different metabolic receptors simultaneously — typically GIP, GLP-1, and glucagon. Retatrutide is the first triple agonist in clinical development for weight loss. The glucagon component is hypothesized to add an energy-expenditure effect on top of GLP-1 and GIP appetite suppression.

View term page →Retatrutide: triple-agonist evidence →

A pancreatic hormone co-secreted with insulin that signals satiety via brainstem receptors. Long-acting amylin analogs (cagrilintide) are being studied alone and combined with GLP-1 drugs (CagriSema) to amplify weight loss beyond what GLP-1 monotherapy achieves. Distinct receptor pathway from GLP-1.

View term page →CagriSema REDEFINE trial results →

Diminishing weight-loss response with continued GLP-1 exposure at a stable dose — a form of pharmacological tolerance. Documented in rodent models and clinically suspected in the ~20% of long-term users who plateau before reaching their goal weight despite continued dosing. Postulated mechanism: GLP-1 receptor downregulation or β-arrestin-mediated desensitization. Microdosing protocols and drug holidays have been proposed to mitigate it, but no randomized data exist.

View term page →Top semaglutide trial reading list →

A small organic molecule that activates the GLP-1 receptor without being built from a peptide chain. Survives stomach acid and digestive enzymes intact, eliminating the food-restriction requirement that hampers oral peptide drugs like Rybelsus. Foundayo (orforglipron) is the first FDA-approved non-peptide GLP-1 agonist (April 2026), opening a class of oral pills that may replace injections for patients with moderate weight-loss needs.

View term page →Foundayo drug overview →

A blood test reflecting average blood glucose over the prior 8-12 weeks, measured as the percentage of red-blood-cell hemoglobin glycated by glucose. Used as the primary endpoint in T2D trials. Diagnostic threshold: ≥6.5% = diabetes; 5.7-6.4% = prediabetes; <5.7% = normal. GLP-1 receptor agonists typically reduce A1C by 1.0-2.0 percentage points at maximum dose — clinically meaningful, because each 1-point drop reduces microvascular complication risk roughly 25-35%.

View term page →GLP-1 trial reading list →

Metabolic Dysfunction-Associated Steatohepatitis (MASH) and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) — the 2023 consensus renamings of NASH and NAFLD. Characterized by hepatic fat accumulation plus inflammation (MASH) or without (MASLD), driven by insulin resistance + obesity. SYNERGY-NASH (Loomba 2024 NEJM, tirzepatide) and ESSENCE (semaglutide phase 3) showed substantial fibrosis improvement, positioning GLP-1s as the first systemic therapies for MASH outside the FXR agonist resmetirom.

View term page →Tirzepatide trial reading list (incl. SYNERGY-NASH) →

The percentage of total body weight lost from baseline, reported as the primary endpoint in modern obesity trials. STEP-1 reported −14.9% TBWL on semaglutide 2.4 mg at 68 weeks; SURMOUNT-1 reported −20.9% TBWL on tirzepatide 15 mg at 72 weeks. TBWL is preferred over absolute kg change because it adjusts for starting body weight — a 15% loss in someone starting at 100 kg (15 kg) and 200 kg (30 kg) is clinically equivalent in metabolic terms.

View term page →STEP-1 trial deep-dive →

A protein fragment released by the pancreas in 1:1 ratio with endogenous insulin. Used clinically to distinguish patients still producing insulin (type 2 diabetes, prediabetes) from those who are not (type 1 diabetes, end-stage type 2). GLP-1 agonists work by augmenting endogenous insulin secretion — patients with very low C-peptide (<0.6 ng/mL) typically respond poorly, which is one reason GLP-1s are FDA-labeled for type 2 (not type 1) diabetes.

View term page →STEP-1 metabolic endpoints →

A blood-based estimate of kidney filtration capacity, expressed in mL/min/1.73m². Normal is ≥90; <60 sustained 3+ months defines chronic kidney disease (CKD). Stage 4 CKD is eGFR 15-29; stage 5 (kidney failure) is <15. The FLOW trial showed semaglutide reduced major kidney-disease events 24% in T2D patients with CKD (Perkovic 2024, PMID 38785209), driving the 2025 FDA label expansion for Ozempic to include kidney-disease progression prevention.

View term page →Top GLP-1 kidney studies →

Fat stored deep inside the abdomen, surrounding organs like the liver, pancreas, and intestines — distinct from subcutaneous fat (under the skin). VAT is more metabolically active and more strongly linked to cardiometabolic disease than subcutaneous fat. GLP-1 receptor agonists preferentially reduce VAT relative to subcutaneous fat in DEXA substudies of STEP-1 and SURMOUNT-1, which helps explain why weight loss on these drugs reverses cardiometabolic risk faster than calorie restriction alone.

View term page →SURMOUNT-1 body-composition endpoints →

The number of apneas (breathing pauses ≥10 seconds) plus hypopneas (breathing reductions with oxygen desaturation) per hour of sleep, measured during polysomnography. Diagnostic thresholds: AHI 5-14 = mild OSA, 15-29 = moderate, ≥30 = severe. SURMOUNT-OSA used AHI reduction as its primary endpoint; tirzepatide 15 mg cut AHI by ~25 events/hour vs placebo.

View term page →SURMOUNT-OSA trial deep-dive →

Sodium N-(8-[2-hydroxybenzoyl] amino) caprylate — the absorption enhancer co-formulated with oral semaglutide (Rybelsus). SNAC transiently increases gastric pH and disrupts the cell membrane just enough to let semaglutide cross into the bloodstream — without SNAC, oral semaglutide bioavailability would be effectively zero. The reason Rybelsus requires a strict 30-minute fast before and after dosing: food disrupts SNAC-semaglutide complex formation. Foundayo (orforglipron) is a non-peptide molecule and doesn't need SNAC, eliminating the food restriction.

View term page →Oral GLP-1 Q&A hub →

Pivotal Phase 3 trial of semaglutide 2.4 mg weekly vs placebo in 1,961 adults with overweight/obesity (Wilding et al, NEJM 2021, PMID 33567185). Mean weight loss 14.9% at 68 weeks.

View term page →STEP-1 side-effect data investigation →

Pivotal Phase 3 trial of tirzepatide 5/10/15 mg weekly vs placebo in 2,539 adults with overweight/obesity (Jastreboff et al, NEJM 2022, PMID 35658024). Mean weight loss 20.9% at 15 mg over 72 weeks.

View term page →Tirzepatide vs semaglutide head-to-head →

Cardiovascular outcomes trial of semaglutide 2.4 mg in 17,604 non-diabetic adults with overweight/obesity and established CV disease (Lincoff et al, NEJM 2023). Major adverse cardiovascular events reduced 20% (HR 0.80, 95% CI 0.72-0.90).

View term page →SELECT trial cardiovascular benefits →

Trial of semaglutide 1 mg weekly in chronic kidney disease + type 2 diabetes (NEJM 2024). Composite kidney outcome (eGFR decline, kidney failure, renal/CV death) reduced 24%, HR 0.76.

View term page →FLOW trial: semaglutide in kidney disease →

Trial of tirzepatide 10/15 mg weekly in obstructive sleep apnea + obesity. Apnea-hypopnea index improved approximately 50% in the tirzepatide arm vs placebo.

View term page →SURMOUNT-OSA trial deep dive →

Trial of semaglutide 2.4 mg in adolescents 12-17 with obesity (Weghuber et al, NEJM 2022). Mean weight reduction 16.7% vs 0.6% placebo. Pediatric trials do not measure facial appearance as an outcome.

View term page →STEP-TEENS adolescent semaglutide →

A composite endpoint used in cardiovascular outcomes trials, typically defined as cardiovascular death + nonfatal myocardial infarction + nonfatal stroke. GLP-1 cardiovascular trials report MACE as the primary endpoint: SELECT (semaglutide in obesity) showed 20% relative risk reduction, SUSTAIN-6 (semaglutide T2D) 26%, LEADER (liraglutide) 13%. Effect size correlates roughly with weight loss but extends beyond what weight reduction alone explains.

View term page →Top GLP-1 cardiovascular studies →

A validated patient-reported outcome measure for heart failure symptoms and physical limitations. Scored 0-100, higher is better. A 5-point improvement is considered clinically meaningful. STEP-HFpEF reported a mean KCCQ-CSS gain of 16.6 points on semaglutide vs 8.7 on placebo (estimated difference 7.8 points) — the primary endpoint that drove the 2024 EMA / FDA filings for semaglutide in HFpEF + obesity.

View term page →Top GLP-1 cardiovascular studies →

Phase 3 randomized trial of orforglipron (Foundayo) for chronic weight management in adults with obesity without diabetes. 72 weeks, N=3,127, conducted across 10 countries (NCT05869903). Primary outcome: −12.4% body weight on 17.2 mg orforglipron vs −0.9% placebo (efficacy estimand); −11.1% vs −2.1% (treatment-regimen estimand). Drove the April 2026 FDA approval of Foundayo — the first FDA-approved oral non-peptide GLP-1 receptor agonist for weight management.

View term page →Foundayo drug overview →

The Impact of Weight on Quality of Life-Lite Clinical Trials version — a 20-item patient-reported outcome questionnaire validated for use in obesity drug trials. Scored 0-100, higher is better; physical-function and psychosocial subdomains are reported separately. Clinically meaningful improvement threshold is ~14.6 points. STEP-1 and SURMOUNT-1 both reported large IWQOL-Lite-CT gains, used by FDA in evaluating quality-of-life claims for Wegovy and Zepbound labeling.

View term page →STEP-1 quality-of-life endpoint →

Semaglutide withdrawal trial that established GLP-1 obesity therapy as chronic — not finite — treatment. After all 803 participants reached the 2.4 mg dose in a 20-week run-in, they were randomized 2:1 to continue semaglutide or switch to placebo for 48 more weeks. Continuers lost another 7.9% body weight; switchers regained 6.9%. Rubino 2021 JAMA, PMID 33755728. Effectively retired the idea of finishing a GLP-1 course.

View term page →STEP-4 trial deep-dive →

Phase 2 randomized trial of tirzepatide in adults with biopsy-confirmed MASH (formerly NASH) + significant fibrosis. Loomba 2024 NEJM (PMID 38856224). Primary endpoint: MASH resolution without worsening fibrosis at week 52 — a histologic endpoint requiring liver biopsy. 62% of patients on 15 mg achieved resolution vs 10% placebo. Positions GLP-1s as first-in-class systemic therapy for MASH outside FXR agonists.

View term page →SYNERGY-NASH trial deep-dive →

First GLP-1 cardiovascular outcomes trial to show MACE reduction. N=9,340 adults with type 2 diabetes + established CVD or high CV risk, randomized to liraglutide vs placebo for median 3.8 years (Marso 2016 NEJM, PMID 27295427). Primary endpoint MACE HR 0.87 (P=0.01). Established the GLP-1-class cardioprotective paradigm before SUSTAIN-6 (semaglutide) confirmed it.

View term page →LEADER trial deep-dive →

First GLP-1 trial dedicated to chronic kidney disease outcomes. N=3,533 adults with type 2 diabetes + CKD, randomized to semaglutide 1 mg vs placebo (Perkovic 2024 NEJM, PMID 38785209). Primary kidney composite reduced 24% (HR 0.76). Stopped early for efficacy. Drove the January 2025 FDA Ozempic label expansion for kidney-disease progression prevention.

View term page →FLOW trial deep-dive →

The phase 3b head-to-head trial comparing tirzepatide (Zepbound) to semaglutide (Wegovy) for chronic weight management in non-diabetic adults with obesity. Aronne and colleagues (NEJM 2025, PMID 40353578) reported tirzepatide -20.2% body weight versus semaglutide -13.7% at 72 weeks — a 6.5-percentage-point advantage for tirzepatide.

View term page →SURMOUNT-5 trial deep-dive →

The phase 3 trial of tirzepatide in adults with obesity AND type 2 diabetes. Garvey and colleagues (Lancet 2023) reported tirzepatide 15 mg producing -14.7% body weight reduction at 72 weeks versus placebo -3.2%, with HbA1c reductions exceeding most diabetes-specific GLP-1 trials. Supported FDA expansion of Zepbound labeling toward T2D-with-obesity populations.

View term page →SURMOUNT-2 trial deep-dive →

The phase 3 trial of tirzepatide after a 12-week intensive lifestyle-intervention lead-in. Wadden and colleagues (Nature Medicine 2023) showed an additional -18.4% body weight change on tirzepatide compared with a 2.5% regain on placebo over the 72-week treatment period following the lifestyle run-in — demonstrating tirzepatide and lifestyle therapy are additive.

View term page →SURMOUNT-3 trial deep-dive →

The phase 3 head-to-head trial of tirzepatide versus semaglutide 1 mg (Ozempic dose) in adults with type 2 diabetes. Frías and colleagues (NEJM 2021) reported tirzepatide 15 mg achieving HbA1c reduction of -2.30 percentage points versus semaglutide -1.86 and body weight -11.2 kg versus -5.7 kg over 40 weeks. The first major head-to-head between the GLP-1 leaders.

View term page →SURPASS-2 trial deep-dive →

The cardiovascular outcomes trial of semaglutide in adults with type 2 diabetes at high cardiovascular risk. Marso and colleagues (NEJM 2016) reported a 26% relative reduction in the three-point MACE composite (cardiovascular death, nonfatal MI, nonfatal stroke). Established the cardiovascular safety + benefit signal that later trials confirmed.

View term page →SUSTAIN-6 trial deep-dive →

The cardiovascular outcomes trial of dulaglutide (Trulicity) in 9,901 adults with type 2 diabetes. Gerstein and colleagues (Lancet 2019) reported a 12% relative reduction in MACE over a median of 5.4 years — the first GLP-1 trial to enroll a majority primary-prevention population (where most participants had not yet had a CV event).

View term page →REWIND trial deep-dive →

The cardiovascular safety trial of oral semaglutide (Rybelsus) in adults with type 2 diabetes at high cardiovascular risk. Husain and colleagues (NEJM 2019) demonstrated noninferiority for MACE — establishing that oral GLP-1 administration delivers the same cardiovascular safety signal as the subcutaneous formulation.

View term page →PIONEER 6 trial deep-dive →

The phase 3 trial of semaglutide 2.4 mg in adults with heart failure with preserved ejection fraction (HFpEF) and obesity. Kosiborod and colleagues (NEJM 2023) reported substantial improvement in Kansas City Cardiomyopathy Questionnaire clinical summary score and 6-minute walk distance — the first GLP-1 trial demonstrating heart-failure-specific symptomatic benefit.

View term page →STEP-HFpEF trial deep-dive →

The cardiovascular outcomes trial of once-weekly exenatide (Bydureon) in 14,752 adults with type 2 diabetes. Holman and colleagues (NEJM 2017) reported a neutral primary outcome — exenatide did not significantly reduce MACE, distinguishing it from the semaglutide / liraglutide / dulaglutide CV-benefit trials.

View term page →EXSCEL trial deep-dive →

The cardiovascular safety trial of lixisenatide (Adlyxin) in adults with type 2 diabetes following an acute coronary syndrome. Pfeffer and colleagues (NEJM 2015) demonstrated cardiovascular safety (noninferiority for MACE) but no superiority — the first GLP-1 cardiovascular outcomes trial completed under the post-2008 FDA CV-safety guidance.

View term page →ELIXA trial deep-dive →

The cardiovascular outcomes trial of efpeglenatide (a long-acting GLP-1 receptor agonist) in adults with type 2 diabetes at high cardiovascular risk. Gerstein and colleagues (NEJM 2021) reported a 27% relative reduction in three-point MACE — efpeglenatide was not subsequently marketed in the US.

View term page →AMPLITUDE-O trial deep-dive →

The cardiovascular outcomes trial of albiglutide (Tanzeum) in 9,463 adults with type 2 diabetes and established cardiovascular disease. Hernandez and colleagues (Lancet 2018) reported a 22% relative reduction in MACE — but GSK had withdrawn albiglutide from global markets the year before the results were published due to low commercial uptake.

View term page →HARMONY OUTCOMES trial deep-dive →

The phase 3 trial of liraglutide 3.0 mg (Saxenda) in adults with obesity AND type 2 diabetes. Davies and colleagues (JAMA 2015) reported -6.0% body weight at 56 weeks on liraglutide versus -2.0% on placebo — establishing the indication-expansion to the T2D + obesity population that Saxenda still serves.

View term page →SCALE Diabetes trial deep-dive →

The phase 3 trial of semaglutide 2.4 mg in adults with overweight or obesity AND type 2 diabetes. Davies and colleagues (Lancet 2021) reported -9.6% body weight at 68 weeks on semaglutide 2.4 mg versus -3.4% on placebo and HbA1c reduction of -1.6 percentage points — the pivotal trial supporting Wegovy use in T2D populations alongside Ozempic.

View term page →STEP 2 trial deep-dive →

The phase 3 trial of tirzepatide in adults with heart failure with preserved ejection fraction (HFpEF) and obesity. Packer and colleagues (NEJM 2025) reported substantial improvement in HFpEF-specific outcomes — the tirzepatide complement to STEP-HFpEF.

View term page →SUMMIT trial deep-dive →

The phase 3 trial of liraglutide 3.0 mg for maintenance of weight loss after a low-calorie diet run-in. Wadden and colleagues (Int J Obes 2013) reported that liraglutide preserved -6.2% of run-in weight loss at 56 weeks versus placebo -0.2% — established the weight-loss-maintenance use case for daily-injectable GLP-1s.

View term page →SCALE Maintenance trial deep-dive →

Gallstones. Listed in Section 5 of every FDA-approved GLP-1 label. Wegovy reports 1.6% vs 0.7% placebo; Saxenda reports 2.2% vs 0.8%. The He et al 2022 meta-analysis pooled the GLP-1 risk at RR 1.37 (95% CI 1.23-1.52).

View term page →GLP-1 + gallbladder/biliary disease →

Functional bowel obstruction. Added to Section 6.2 (Postmarketing Experience) of every GLP-1 label in 2023. Sodhi JAMA 2023 cohort found HR 4.22 for bowel obstruction; the Ueda Scandinavian cohort 2024 found HR 0.83 — evidence is mixed.

View term page →GLP-1 + ileus / bowel obstruction →

Diffuse hair shedding triggered by rapid weight loss or metabolic stress. Typically self-resolving over 3-6 months with adequate protein and micronutrient intake.

View term page →GLP-1 fatigue + hair loss + duration →

Patient term for facial volume loss with rapid weight loss on a GLP-1. The 2025 Otolaryngology imaging cohort (PMID 40407186) quantified it at median 9% midfacial volume loss with about 7% loss per 10 kg total weight lost.

View term page →Ozempic face: facial volume loss evidence →

Rare neuroendocrine tumor of thyroid C-cells. GLP-1 medications carry a black-box warning based on rodent data; no increased human MTC incidence has been demonstrated. Contraindicated in patients with personal/family history of MTC or MEN-2.

View term page →Does GLP-1 cause cancer? MTC evidence →

Loss of muscle, bone, and other non-fat tissue with rapid weight loss. STEP-1 DEXA sub-analysis found roughly 39% of weight lost was lean mass. Mitigated with adequate protein and resistance training.

View term page →Semaglutide and muscle mass: STEP DEXA sub-analyses →

Delayed gastric emptying severe enough to cause persistent nausea, vomiting, or food retention after a GLP-1 dose. A 2023 JAMA case-control study (PMID 37335445) found GLP-1 use associated with a 3.7-fold increased risk of clinically diagnosed gastroparesis vs bupropion-naltrexone. Risk rises with higher doses, faster titration, and pre-existing diabetic autonomic neuropathy. Symptoms usually resolve within 4-8 weeks of dose reduction or discontinuation.

View term page →Side-effect timeline tool →

Inflammation of the pancreas, listed as a labeled warning for every approved GLP-1 receptor agonist. Mechanism is uncertain but appears to involve cholelithiasis-triggered duct obstruction rather than direct pancreatic toxicity. Pooled FDA AERS data shows incidence ~0.2-0.4% over typical treatment durations — elevated vs background ~0.05%/year but absolute risk remains low. Patients with prior pancreatitis, heavy alcohol use, or symptomatic gallstones should weigh risk:benefit carefully.

View term page →Side-effect timeline tool →

An early concern from rodent studies (acinar-cell hyperplasia in some animal models). Large human cohort studies and the SELECT cardiovascular outcomes trial (Lincoff 2023, PMID 37952131) have NOT shown an elevated pancreatic-cancer signal over years of follow-up. The 2024 FDA Drug Safety Communication confirmed no causal association established. The boxed warning on GLP-1 labels covers thyroid C-cell tumors (rodent data) and acute pancreatitis (small absolute risk), but NOT pancreatic cancer.

View term page →SELECT trial deep-dive (long-term safety) →

Localized swelling or thickening of subcutaneous fat at recurrently-used injection sites — common in patients who inject GLP-1s in the same spot weekly. Lipohypertrophic tissue absorbs the drug erratically, causing unpredictable appetite suppression and weight-loss outcomes. Prevention: rotate at least 2 inches between consecutive doses, cycling abdomen → thigh → upper arm over 8 weeks.

View term page →Injection-site rotation cheat sheet →

A condition of delayed gastric emptying — food stays in the stomach longer than normal — causing nausea, vomiting, early satiety, and abdominal pain. GLP-1 medications slow gastric emptying as part of their mechanism; this is generally beneficial for weight loss but can produce symptomatic gastroparesis in a small fraction of patients, particularly with rapid dose escalation.

View term page →GLP-1 and slowed gastric emptying →

Progressive loss of skeletal muscle mass and function. Rapid weight loss — whether from bariatric surgery, GLP-1 therapy, or calorie restriction — accelerates muscle loss alongside fat loss. Mitigation focuses on adequate dietary protein (1.0-1.6 g/kg/day) and resistance training during active weight-loss phases.

View term page →GLP-1 muscle-loss prevention protocol →

A measurement of bone strength expressed as grams of mineral per square centimeter, typically measured by DXA scan. Significant weight loss (>10%) is associated with mild BMD reduction whether from bariatric surgery, GLP-1 therapy, or other interventions. Resistance training, adequate dietary calcium + vitamin D, and avoiding excessive caloric deficit help preserve BMD.

View term page →GLP-1 bone density and fracture risk →

A constellation of symptoms (nausea, abdominal cramping, diarrhea, dizziness, sweating) triggered by rapid emptying of high-osmolar food contents into the small intestine. Common after bariatric surgery, particularly Roux-en-Y gastric bypass. Distinct from GLP-1-induced gastroparesis (the opposite mechanism — delayed gastric emptying).

View term page →Bariatric surgery vs GLP-1 →

An inflammatory skin condition affecting body folds (under the breasts, abdomen, thighs, axillae) caused by friction, moisture, and secondary bacterial or fungal infection. Chronic intertrigo refractory to ≥3 months of medical therapy is the most-cited medical-necessity criterion for insurance coverage of panniculectomy and other post-weight-loss body-contouring procedures.

View term page →Skin-removal cost + insurance qualifier →

Prescription GLP-1 medications prepared from bulk active ingredient by a 503A or 503B pharmacy rather than the FDA-approved branded product. Legality and quality vary; FDA-approved products are off the shortage list as of late 2024.

View term page →Compounded semaglutide bioequivalence →

Traditional state-licensed compounding pharmacy that prepares medications for individual patients with a prescription. Subject to USP <797> standards but not FDA pre-approval of finished products.

View term page →PCAB accreditation investigation →

FDA-registered facility licensed to compound medications without a patient-specific prescription, in larger volumes than a 503A. Subject to FDA inspection and stricter quality oversight than 503A.

View term page →PCAB accreditation investigation →

Pharmacy Compounding Accreditation Board certification, administered by ACHC. A voluntary third-party quality program covering sterility, potency verification, and facility standards. Required for some 503B outsourcing facilities.

View term page →PCAB accreditation investigation →

The United States Pharmacopeia chapter governing sterile compounding for human use, covering air quality, personnel garbing, surface sampling, and beyond-use dating for compounded preparations. 503A pharmacies must demonstrate USP <797> compliance to dispense sterile injectables like compounded semaglutide. Inspections typically check ISO Class 5 primary engineering controls, anteroom pressure differentials, and operator media-fill testing.

View term page →Pharmacy legitimacy lookup tool →

Two FDA categories for sterile compounding pharmacies. 503A: state-licensed pharmacies that compound patient-specific prescriptions (must hold a valid prescription with a named patient). 503B: voluntarily-registered outsourcing facilities that can compound in bulk without prescriptions, must comply with full Current Good Manufacturing Practice (cGMP) standards.

View term page →Compounded vs brand Q&A hub →

Formal FDA enforcement document citing specific regulatory violations and demanding corrective action. We track every warning letter sent to compounded GLP-1 telehealth providers and pharmacies.

View term page →FDA warning letters to GLP-1 providers (live database) →

Insurance requirement that a prescriber submit clinical justification before a medication will be covered. Common for GLP-1 weight-loss drugs given the high list price; turnaround typically 24-72 hours.

View term page →GLP-1 prior auth letter generator (tool) →

Insurance requirement to try cheaper or older medications before authorizing newer/more expensive options. A common access barrier for GLP-1 weight-loss drugs.

View term page →GLP-1 insurance coverage: Medicare, Medicaid, commercial →

Prescribing an FDA-approved drug for a condition or population not on its label. Legal and common — Ozempic for weight loss is the canonical example. Insurance coverage may not extend to off-label indications.

View term page →How to get a GLP-1 prescription →

Public FDA database tracking medications in short supply. Compounded GLP-1s were widely produced under the shortage exemption while semaglutide and tirzepatide were on the list (off the list as of late 2024).

View term page →Compounded GLP-1 price movement (12-month analysis) →

The cost-share level a prescription drug occupies in an insurance plan's formulary (covered drug list). Tier 1 = generic ($), Tier 2 = preferred brand ($$), Tier 3 = non-preferred brand ($$$), Tier 4 = specialty (highest copay). Wegovy and Zepbound are typically Tier 3 or 4 on commercial plans — meaning copays of $100-$500+/month even after approval. Some plans exclude them entirely. Generic GLP-1s do not yet exist (semaglutide patent runs through 2032 in the US).

View term page →Insurance coverage Q&A hub →

A middleman company that administers the prescription-drug benefit for an insurer or employer, including formulary design, prior-authorization criteria, pharmacy network contracts, and rebate negotiations with manufacturers. The three largest US PBMs (Express Scripts, CVS Caremark, OptumRx) control ~80% of the market and meaningfully shape GLP-1 access.

View term page →How GLP-1 coverage works by plan type →

An insurance plan design that prevents manufacturer copay-card assistance from counting toward the patient's deductible or out-of-pocket maximum. The patient still benefits from the manufacturer card during the assistance period but resumes paying full out-of-pocket costs once the card runs out. Common on commercial high-deductible plans for high-cost specialty drugs like GLP-1s.

View term page →Coupon and cash-pay channel guide →

A pharmacy specifically credentialed to dispense high-cost, complex-handling medications including biologics, injectables, and certain GLP-1s. Many commercial plans route Wegovy / Zepbound / Mounjaro through a contracted specialty pharmacy rather than a retail chain. The specialty channel adds clinical-monitoring requirements but can streamline prior-authorization.

View term page →How to verify a pharmacy is legitimate →

A pharmacy that fills prescriptions by mail (usually 90-day supplies) rather than in-person pickup. Most commercial plans offer mail-order through their PBM at lower copays for maintenance medications. GLP-1 medications shipped via mail-order require refrigerated handling and cold-chain logistics.

View term page →GLP-1 storage and shelf-life guide →

A formulary restriction that limits how much of a medication can be dispensed per fill, typically expressed as units per 28-day or 30-day supply. For GLP-1s, quantity limits commonly enforce one pen or one vial per 28 days even if a clinician prescribes more — a common appeal trigger for stockpiling during shortages.

View term page →GLP-1 prior-authorization appeal strategy →

A short-term prescription used to maintain continuity of care during a supply disruption — for example, switching a Wegovy patient temporarily to compounded semaglutide during an FDA shortage, or to Ozempic at a lower dose during a Wegovy stockout. The intent is to bridge the patient back to the original drug once supply returns.

View term page →Switching between GLP-1 medications →

A manufacturer-sponsored program providing free or discounted medication to qualifying low-income patients without insurance coverage. Novo Nordisk's NovoCare and Eli Lilly's LillyCares run separate PAPs for their GLP-1 portfolios, each with income thresholds (typically ≤400% federal poverty level) and recertification windows.

View term page →Paying for a GLP-1 without insurance →

A copay-reduction card issued by the drug manufacturer to lower the patient's out-of-pocket cost at the pharmacy counter. Novo Nordisk's Wegovy SavingsCard and Eli Lilly's Zepbound SavingsCard cap copays at $0 / $25 for commercial-insurance patients meeting eligibility rules. Excluded for federal-program (Medicare, Medicaid, VA, TRICARE) beneficiaries.

View term page →Coupon and cash-pay channel guide →

The dollar amount a patient must pay out-of-pocket for covered health services before the insurance plan starts paying its share. High-deductible health plans (HDHPs) commonly have deductibles of $1,500-$8,000 — meaning a Wegovy patient may pay the full ~$1,000+ monthly cash price out-of-pocket until the deductible is met.

View term page →GLP-1 savings calculator →

The percentage of a covered medical cost a patient pays after meeting the deductible. A 20% coinsurance plan with a $1,000 monthly Wegovy bill means the patient pays $200 and the insurer pays $800. Distinct from a copay (a fixed dollar amount). Coinsurance typically applies until the annual out-of-pocket maximum is reached.

View term page →GLP-1 savings calculator →

Gradual dose escalation to minimize side effects. Tirzepatide's standard schedule steps every 4 weeks (2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg). Slower titration reduces nausea and the rate of facial volume change.

View term page →GLP-1 titration planner (tool) →

Time for plasma concentration to fall by half. Semaglutide ~7 days. Tirzepatide ~5 days. Liraglutide ~13 hours (daily dosing). Orforglipron ~36 hours. Determines weekly vs daily dosing and washout timing.

View term page →How long does a GLP-1 stay in your system →

Time between stopping one GLP-1 and starting another (or before pregnancy planning). The Wegovy label recommends discontinuing at least 2 months before a planned pregnancy.

View term page →GLP-1 washout calculator (tool) →

Skipped weekly injection. For semaglutide and tirzepatide: take within 5 days of the missed dose; if more than 5 days have passed, skip the missed dose and resume the schedule.

View term page →GLP-1 missed-dose guide (tool) →

Stalling weight loss after months of progress. Mechanisms include metabolic adaptation, behavior drift, and dose ceiling. Often resolves with re-titration, dietary review, or resistance training.

View term page →Why am I not losing weight on a GLP-1? →

Off-label use of sub-therapeutic GLP-1 doses to minimize side effects or extend supply. Limited evidence; the published RCT data was conducted at the FDA-approved doses.

View term page →Semaglutide microdosing evidence →

Moving from one GLP-1 to another (e.g., semaglutide to tirzepatide). Generally requires re-titration; the prior drug's washout time and the new drug's titration plan both matter.

View term page →Switching between GLP-1 medications guide →

Rapid regain of body weight following GLP-1 discontinuation. The STEP-1 withdrawal extension (Wilding 2022 Diabetes Obes Metab, PMID 35441470) showed participants who stopped semaglutide 2.4 mg after 68 weeks regained two-thirds of their lost weight within one year, with restoration of pre-treatment metabolic risk markers. The data reframed GLP-1 obesity treatment as chronic-disease therapy, like blood-pressure medication, rather than a finite intervention.

View term page →STEP-1 withdrawal extension on our top studies list →

The American Society of Anesthesiologists 2023 guidance recommends holding daily GLP-1s for 1 day and weekly GLP-1s for 1 week before procedures requiring anesthesia, due to elevated aspiration risk from delayed gastric emptying. Updated 2024 guidance is less strict (hold not strictly required if NPO ≥18 hours and clinical judgment supports proceeding). Endoscopy patients on GLP-1s have ~6× increased rate of retained gastric contents.

View term page →Side-effect timeline tool →

Injection into the fatty layer just below the skin (not into muscle). All FDA-approved injectable GLP-1 receptor agonists — Wegovy, Ozempic, Zepbound, Mounjaro, Saxenda, Victoza, Trulicity — use subq dosing. Approved injection sites: abdomen (≥2 inches from the navel), front of thigh, or back of upper arm. Rotate weekly to reduce lipohypertrophy. Inject at room temperature for less discomfort.

View term page →Wegovy dose-ladder cheat sheet →

All approved GLP-1 receptor agonists carry a pregnancy precaution and are recommended to be discontinued at least 2 months (semaglutide, given its long half-life) before a planned conception. Animal studies show developmental toxicity at human-equivalent doses. No randomized human-pregnancy data exist; observational registries are accumulating. Patients of reproductive age should use reliable contraception. Inadvertent GLP-1 exposure in early pregnancy is not a guaranteed indication for termination — discuss with a maternal-fetal medicine specialist.

View term page →Wegovy cheat sheet (red flags) →

Structured weight-management counseling delivered by a registered dietitian or qualified clinician — typically 30 visits over 12-14 months, with a target of 1,000-1,500 kcal/day diet + ≥200 min/week physical activity. Required adjunct in some insurance prior-authorization criteria for Wegovy and Zepbound. STEP-3 (semaglutide + IBT) and SURMOUNT-3 (tirzepatide + IBT) showed GLP-1s and IBT are additive, not redundant.

View term page →STEP-3 trial deep-dive →