Tool · Updated June 13, 2026

GLP-1 glossary

Every term you'll meet researching GLP-1 medications — the drugs, the pharmacy and insurance jargon, the clinical words — defined in plain English and linked to the guides that go deeper.

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503A pharmacy Pharmacy & sourcing

A state-licensed compounding pharmacy that prepares customized medications for one patient at a time, against an individual prescription. 503A pharmacies are overseen mainly by state boards, not the FDA, and the products they compound are not FDA-approved. If you're considering a compounded GLP-1, knowing whether a 503A or a 503B made it tells you a lot about the manufacturing standards behind it.

503B outsourcing facility Pharmacy & sourcing

A compounding facility that registers with the FDA and follows federal manufacturing standards (cGMP), allowing it to make larger batches than a 503A pharmacy. 503B facilities typically supply clinics and hospitals and face tighter oversight, though their products are still not FDA-approved drugs. The stricter standards are why 503B sourcing is generally considered lower-risk than 503A for compounded medications.

A

A1c (HbA1c) Clinical

A blood test that estimates your average blood sugar over the past two to three months, reported as a percentage. It's the main number used to diagnose and track type 2 diabetes and prediabetes — broadly, 5.7–6.4% is prediabetes and 6.5% or higher is diabetes. GLP-1 medications often lower A1c, which is why prior-authorization letters for diabetes coverage usually require a recent value.

Active pharmaceutical ingredient (API) Pharmacy & sourcing

The component of a medication that actually does the work — for example, semaglutide is the API inside Wegovy and Ozempic. Everything else in the product (stabilizers, preservatives, liquid) is an inactive ingredient, or excipient. With compounded drugs, where the API is sourced and whether it's the exact same molecule as the branded version is a key safety question.

Adherence Clinical

How consistently you actually take a medication as prescribed — the right dose, on schedule, over time. It matters a lot with GLP-1s because much of the published weight-loss data comes from people who stayed on treatment for a year or more, and results fade if doses are skipped or stopped. Insurance hurdles, side effects, and cost are the most common reasons adherence slips.

Related: Titration Maintenance dose

Appeal (insurance) Cost & insurance

A formal request asking your insurer to reverse a denied claim or prior authorization. Appeals succeed more often than people expect, and most plans must respond within a set window; if the internal appeal fails, you usually have a right to an external review by an independent party. The key is documenting why the covered alternatives don't work for you.

See also: Appeal letter templates

B

BMI (Body Mass Index) Clinical

A number calculated from your height and weight (weight in kg ÷ height in m²) used as a rough screening tool for weight categories — generally 25–29.9 is "overweight" and 30+ is "obesity." Insurers and FDA labels often use BMI thresholds to decide coverage and eligibility (for example, a GLP-1 may be labeled for BMI 30+, or 27+ with a weight-related condition). BMI is a blunt instrument that ignores muscle and body composition, but it's the gatekeeping number in practice.

Related: Comorbidity Lean mass loss

Branded drug Pharmacy & sourcing

A medication sold under a manufacturer's trade name, made by that manufacturer and reviewed and approved by the FDA — for example, Wegovy, Zepbound, or Ozempic. Branded products come in a tested device (like a prefilled pen) with an approved label, which is the main distinction from compounded copies. They're usually the most expensive option at list price, though insurance and manufacturer programs can change that.

C

Cardiometabolic Clinical

An umbrella term for conditions that link heart health and metabolism — things like type 2 diabetes, high blood pressure, abnormal cholesterol, and obesity, which tend to cluster together. GLP-1 medications are increasingly studied for cardiometabolic benefits beyond weight, including blood sugar and cardiovascular risk. Providers that frame their program as "cardiometabolic" usually emphasize lab monitoring and whole-picture care.

Cardiovascular outcomes trial (CVOT) Clinical

A large, long clinical trial that measures whether a drug changes the rate of real cardiac events — heart attack, stroke, cardiovascular death — not just risk markers like cholesterol. These trials are expensive and take years, so a completed one is a strong evidence signal. Wegovy's SELECT trial is the landmark example in the GLP-1 class, showing reduced major cardiac events in people with existing heart disease.

See also: Wegovy vs. Zepbound

Comorbidity Clinical

A second health condition you have alongside the main one being treated — for weight management, common examples are type 2 diabetes, high blood pressure, sleep apnea, or high cholesterol. Comorbidities matter for coverage: many GLP-1s are labeled for a lower BMI threshold (often 27+) when a weight-related comorbidity is present. Documenting them is often what unlocks insurance approval.

Compounded medication Pharmacy & sourcing

A version of a drug mixed by a pharmacy rather than produced by the original manufacturer. Compounded semaglutide and tirzepatide became widely sold during the 2022–2025 shortages, but that exception largely ended once the shortages were declared over, followed by a major FDA enforcement wave in 2026. Compounded drugs are not FDA-approved, and quality depends heavily on the pharmacy — which is why we score providers partly on sourcing.

Copay card / manufacturer savings program Cost & insurance

A discount program run by a drug's manufacturer that lowers your out-of-pocket cost, sometimes to as little as $0–$25 a month if you have commercial insurance. They come with eligibility rules (often excluding government plans like Medicare and Medicaid) and caps, so the advertised "as low as" price isn't guaranteed for everyone. Always check the fine print and whether the savings apply for your whole course, not just the first month.

CPA (cost per acquisition) Industry

The commission an advertiser pays a publisher or affiliate when a referred person signs up or buys — "cost per acquisition." In the GLP-1 telehealth space these payouts can be substantial, which creates an obvious conflict of interest for review sites. We name it here for transparency: on this site, scores are locked before anyone checks a provider's CPA, and the figure is never published — see our methodology and pledge.

D

Direct-to-consumer (DTC) Industry

A model where a company sells a product or service straight to the public, bypassing the traditional middlemen — in this space, telehealth platforms that prescribe and ship GLP-1s without you visiting an in-person clinic. DTC made treatment far more accessible, but it also concentrated marketing dollars and affiliate commissions, so the loudest brand isn't always the best-scored one. Convenience and quality of care don't always move together.

Dyslipidemia Clinical

An unhealthy balance of fats in the blood — typically high LDL ("bad") cholesterol or triglycerides, low HDL ("good") cholesterol, or a mix. It's a common comorbidity in weight management and part of the cardiometabolic picture GLP-1 treatment can improve. Some people on these medications are able to reduce or stop lipid-lowering drugs, though that's a decision for your prescriber.

Related: Cardiometabolic Comorbidity

E

Excipient Pharmacy & sourcing

An inactive ingredient in a medication — buffers, stabilizers, preservatives, or the liquid an injection is dissolved in — everything that isn't the active pharmaceutical ingredient. Excipients affect how a drug is stored, how it feels going in, and occasionally whether someone has a reaction. With compounded products, the excipients can differ from the branded version even when the active ingredient is the same.

F

FDA approval Pharmacy & sourcing

The U.S. Food and Drug Administration's sign-off that a specific drug, at a specific dose and form, is safe and effective for a specific use, made under reviewed manufacturing standards. Approval is tied to the exact product — which is why a compounded copy or a different salt form is not "FDA-approved" even if it contains a similar molecule. It's the strongest single quality signal in the whole system.

FDA drug shortage list Pharmacy & sourcing

An official FDA list of medications currently in short supply. It matters for GLP-1s because, while a drug is listed, pharmacies are allowed to compound copies of it — the legal basis for the compounded-semaglutide boom. When the FDA declared the semaglutide and tirzepatide shortages resolved in 2024–2025, that exception closed, and mass-market compounding of copies became an enforcement target.

Food noise Clinical

The constant background mental chatter about food — cravings, planning the next meal, thinking about snacks you're trying to resist. Many GLP-1 users describe the quieting of food noise as the single most life-changing effect of treatment, often more striking than the number on the scale. It's not an official medical term, but it shows up so consistently in patient reports that clinicians now use it too.

Formulary Cost & insurance

The list of medications your insurance plan agrees to cover, usually sorted into tiers that determine your copay. If a drug isn't on the formulary, you'll pay full price unless you win a formulary exception. Formularies change yearly and mid-year, which is why people are sometimes forced to switch GLP-1s even when their current one is working.

See also: Appeal letter templates

Formulary exclusion Cost & insurance

When a specific drug is deliberately left off your plan's covered list, so the insurer won't pay for it at all. You can request a formulary exception, which usually requires your prescriber to document why the covered alternatives are inappropriate for you. These exclusions are a common reason people on a working GLP-1 suddenly lose coverage.

See also: Appeal letter templates

Foundayo (orforglipron) Medications

A brand name for orforglipron, an oral (pill) GLP-1 medication from Eli Lilly approved for weight management in 2026. As a once-daily pill with fewer food-and-water timing restrictions than older oral options, it's notable for people who want to avoid injections. As a newer product, its long-term real-world track record is still thinner than the established injectables.

FSA (Flexible Spending Account) Cost & insurance

An employer-offered account that lets you set aside pre-tax money for eligible health costs, which can include prescription GLP-1s and sometimes telehealth fees. The catch is the "use it or lose it" rule — funds usually don't roll over year to year — so timing your spending matters. Keep receipts, since membership-style telehealth fees aren't always reimbursable without documentation.

G

Gastroparesis Clinical

A condition where the stomach empties unusually slowly, causing nausea, bloating, and feeling full quickly. GLP-1 medications slow stomach emptying on purpose — that's part of how they curb appetite — and in some people this can tip into more serious, persistent symptoms. Severe or lasting symptoms are worth raising with your prescriber rather than enduring.

Generic drug Pharmacy & sourcing

An FDA-approved copy of a branded medication, made after the original's patent expires, with the same active ingredient and proven to work equivalently — usually at a much lower price. Importantly, true generics of the newer GLP-1s (semaglutide, tirzepatide) do not yet exist in the U.S., because the drugs are still under patent. "Cheap semaglutide" sold today is almost always compounded, not generic — an important distinction.

GIP receptor Clinical

A second gut-hormone receptor (glucose-dependent insulinotropic polypeptide) that, alongside GLP-1, influences blood sugar and appetite. Tirzepatide acts on both GIP and GLP-1 receptors — a "dual agonist" — which is the mechanistic reason it tends to produce somewhat greater average weight loss than GLP-1-only drugs like semaglutide. Newer pipeline drugs add even more targets.

See also: Wegovy vs. Zepbound

GLP-1 (glucagon-like peptide-1) Clinical

A hormone your gut releases after eating that signals fullness and helps regulate blood sugar. GLP-1 medications mimic this hormone — which is why they reduce appetite and are used for both type 2 diabetes and weight management. "GLP-1" is now used loosely to mean the whole class of these drugs, including ones (like tirzepatide) that also act on other receptors.

H

HSA (Health Savings Account) Cost & insurance

A tax-advantaged savings account paired with a high-deductible health plan, usable for eligible medical expenses including prescription GLP-1s. Unlike an FSA, HSA funds roll over indefinitely and are yours to keep, which makes them useful for budgeting an ongoing medication. As with FSAs, membership-style telehealth fees may need documentation to qualify.

I

Insulin resistance Clinical

When your cells stop responding well to insulin, so your body makes more of it to keep blood sugar in check — a core driver of prediabetes and type 2 diabetes. It's closely tied to weight and the broader cardiometabolic picture. GLP-1 medications can improve blood sugar control, which is part of why they're used in diabetes as well as weight management.

L

Lean mass loss Clinical

Muscle and other non-fat tissue lost alongside fat during weight loss. A portion of any rapid weight loss — including on GLP-1s — is lean mass, which matters more as you age because muscle is harder to rebuild. Clinicians typically recommend resistance exercise and adequate protein to protect muscle, and it's the most common regret among people who lost weight very fast.

LillyDirect Industry

Eli Lilly's direct-to-patient platform for buying its own branded medications (such as Zepbound and Mounjaro), sometimes including self-pay vial options at lower prices than the list price. It's a manufacturer channel, not a compounding service — the product is the authentic, FDA-approved drug. Several telehealth providers integrate with it to fulfill brand-name prescriptions.

Liraglutide Medications

An older GLP-1 medication, sold as Saxenda for weight management and Victoza for diabetes, taken as a daily (rather than weekly) injection. It generally produces less weight loss than the newer weekly drugs semaglutide and tirzepatide, and the daily dosing is less convenient. It still has a role, and a lower-cost generic version has become available, unlike the newer agents.

M

Maintenance dose Clinical

The steady, ongoing dose you settle on after finishing the gradual dose-escalation (titration) phase — the level meant to deliver the medication's full effect long term. For Wegovy the standard maintenance dose is 2.4 mg weekly; for Zepbound it can be 5, 10, or 15 mg. Many people stay below the maximum if a lower dose is working and better tolerated.

Medicare coverage (for GLP-1s) Cost & insurance

How the federal Medicare program pays — or doesn't — for GLP-1 medications. By law Medicare has been barred from covering drugs used purely for weight loss, though it does cover them for diabetes and certain other approved uses (such as cardiovascular risk reduction and sleep apnea). That's now shifting: a temporary CMS demonstration, the Medicare GLP-1 Bridge, covers Wegovy, Zepbound, and Foundayo for obesity at a flat $50/month copay for eligible Part D members from July 1, 2026 through December 31, 2027 — though the underlying statutory weight-loss exclusion still stands. For the 50-and-over audience this is often the single biggest cost question, so verify current specifics for your plan.

Mounjaro Medications

Eli Lilly's brand name for tirzepatide approved for type 2 diabetes. It contains the same active ingredient as Zepbound (which is the brand approved for weight management) — same molecule, different label and indication. People sometimes use Mounjaro off-label for weight loss, which has insurance and access implications.

N

NAION Clinical

Non-arteritic anterior ischemic optic neuropathy — a rare condition involving sudden, usually painless vision loss in one eye from reduced blood flow to the optic nerve. European regulators have listed it as a very rare possible side effect of semaglutide (on the order of 1 in 10,000), and as of mid-2026 the U.S. FDA had not added it to the label. Regardless of suspected cause, sudden vision change is an emergency — seek care immediately.

Related: Semaglutide Pancreatitis

NovoCare Industry

Novo Nordisk's patient-support and direct-purchase platform for its own products (such as Wegovy and Ozempic), which can include savings programs and self-pay pharmacy options. Like LillyDirect, it's a manufacturer channel supplying the authentic, FDA-approved branded drug — not compounding. Telehealth providers often route brand-name fulfillment through it.

O

Off-label prescribing Clinical

When a clinician legally prescribes an FDA-approved drug for a use, dose, or group that isn't on its official label — for example, using diabetes-labeled Ozempic or Mounjaro for weight loss. Off-label prescribing is common and legal, but it can affect insurance coverage, since plans often tie coverage to the approved indication. It's different from using a non-approved compounded product.

Orforglipron Medications

An oral (pill) GLP-1 medication from Eli Lilly, sold under the brand name Foundayo, approved for weight management in 2026. Unlike injectable GLP-1s and the older oral semaglutide, it's a small-molecule pill without strict food-and-water timing rules, which makes it attractive to needle-averse patients. Being new, its long-term and real-world data are still accumulating.

Ozempic Medications

Novo Nordisk's brand name for semaglutide approved for type 2 diabetes, taken as a weekly injection. It contains the same active ingredient as Wegovy (the brand approved for weight management) — same molecule, different label. Because of its fame, "Ozempic" is often used loosely to mean any GLP-1, and it's frequently prescribed off-label for weight loss.

P

Pancreatitis Clinical

Inflammation of the pancreas, which causes severe, persistent abdominal pain that often radiates to the back, sometimes with vomiting. It's an uncommon but serious risk flagged on GLP-1 labels, and it's a reason to stop the medication and seek care rather than wait it out. Severe abdominal pain that won't pass is never "normal adjustment."

Related: Gastroparesis NAION Titration

Patent cliff Industry

The point when a drug's patents expire and lower-cost generics can enter the market, usually causing prices to fall sharply. The newer GLP-1s are years away from this — their patents extend well into the 2030s — which is why no true generic semaglutide or tirzepatide exists yet and prices remain high. Understanding the patent timeline explains why "cheap" versions today are compounded, not generic.

Placebo-controlled trial Clinical

A study where some participants receive an inactive dummy treatment for comparison, so researchers can isolate the drug's true effect. Weight-loss results from these trials are reported as the difference versus placebo — which is why a trial's headline number and a marketing claim can differ. It's a basic marker of trustworthy evidence, and we note who funded each key trial.

Prediabetes Clinical

Blood sugar that's higher than normal but not yet in the diabetes range — typically an A1c of 5.7–6.4%. It's a warning stage where intervention can prevent progression to type 2 diabetes, and weight loss is one of the most effective levers. Many people discover prediabetes during the lab work that comes with starting a weight-management program.

Prior authorization (PA) Cost & insurance

Your insurer's requirement that your prescriber justify a medication, with documentation, before the plan will cover it. It's the single most common paperwork hurdle for GLP-1 coverage and a frequent source of delays. A well-documented PA letter — citing your diagnosis, prior treatments tried, and the relevant guidelines — is what gets it approved.

R

Rybelsus Medications

Novo Nordisk's oral (pill) form of semaglutide, approved for type 2 diabetes. It must be taken on an empty stomach with a small sip of water and a wait before eating, which makes the routine fussier than newer oral options. An oral semaglutide approved specifically for weight management arrived later and is distinct from Rybelsus.

S

Salt form (semaglutide sodium / acetate) Pharmacy & sourcing

A chemically altered version of a drug's active ingredient — for example, semaglutide sodium or semaglutide acetate rather than plain semaglutide. These salt forms have not been studied in humans the way the approved drug has, and the FDA has been explicit that they don't qualify for legitimate compounding. If you see "sodium" or "acetate" attached to a compounded GLP-1, treat it as a red flag.

Saxenda Medications

Novo Nordisk's brand name for liraglutide approved for weight management, taken as a daily injection. It's an older GLP-1 that generally delivers less weight loss than the newer weekly drugs and requires injecting every day. It still appears in some provider line-ups, sometimes as a fallback when newer options aren't covered or tolerated.

Related: Liraglutide Wegovy Zepbound

Semaglutide Medications

The active ingredient in Wegovy (for weight management), Ozempic (for type 2 diabetes), and Rybelsus (an oral diabetes pill). It's a once-weekly injectable GLP-1 receptor agonist (the oral forms differ), and it has the most extensive long-term outcomes evidence in the class, including a completed cardiovascular trial. "Compounded semaglutide" refers to non-FDA-approved copies, which are a separate safety question.

See also: Wegovy vs. Zepbound

Starter dose Clinical

The deliberately low dose you begin on for the first few weeks, meant to let your gut adapt rather than to drive weight loss. Wegovy starts at 0.25 mg weekly and Zepbound at 2.5 mg weekly, each for four weeks before stepping up. Feeling little effect — good or bad — at the starter dose is normal and expected.

Related: Titration Maintenance dose

Step therapy Cost & insurance

An insurance rule that requires you to try (and fail on) one or more cheaper or preferred medications before the plan will cover the one your prescriber actually wants — sometimes called "fail first." It's a common obstacle for GLP-1 coverage. Documenting the alternatives you've already tried and why they didn't work is the path through it.

See also: Appeal letter templates

T

Telehealth Industry

Receiving medical care — consultations, prescriptions, follow-ups — remotely by video, phone, or messaging rather than in person. Telehealth is how most people now access GLP-1 programs, and quality varies widely between providers, from board-certified physician oversight to rubber-stamp questionnaires. Care depth and screening are exactly what our provider scoring weighs.

Tirzepatide Medications

The active ingredient in Zepbound (for weight management) and Mounjaro (for type 2 diabetes). It's a once-weekly injectable that acts on two gut-hormone receptors — GLP-1 and GIP — which is why head-to-head trial data shows somewhat greater average weight loss than semaglutide. As with semaglutide, "compounded tirzepatide" refers to non-FDA-approved copies.

See also: Wegovy vs. Zepbound

Titration Clinical

The schedule of gradually increasing your dose over weeks or months, starting low and stepping up — usually every four weeks — until you reach your maintenance dose. GLP-1s are titrated specifically to reduce side effects like nausea, which tend to cluster in the days after each increase and then fade. Going slower than the standard schedule is a legitimate, label-permitted option if a dose is hard to tolerate.

True cost (all-in pricing) Cost & insurance

What a GLP-1 program actually costs you per month once everything is added up — membership or visit fees, the medication itself, labs, and shipping — rather than the advertised "from" price, which is often just the first month or excludes the drug. Telehealth pricing frequently separates a low membership fee from a much larger medication cost. Calculating the six-month average is the honest way to compare providers.

Type 2 diabetes Clinical

A condition where the body doesn't use insulin effectively and blood sugar runs high, strongly linked to weight and insulin resistance. Several GLP-1s were first approved for type 2 diabetes (Ozempic, Mounjaro) before their weight-management siblings (Wegovy, Zepbound) arrived. Whether a drug is labeled for diabetes or weight loss affects both your insurance coverage and which brand you're prescribed.

W

Wegovy Medications

Novo Nordisk's brand name for semaglutide approved specifically for weight management, given as a weekly injection (an oral version arrived later). It shares its active ingredient with Ozempic but carries the weight-loss label and has a completed cardiovascular outcomes trial behind it. It's one of the two most-prescribed weight-management GLP-1s, alongside Zepbound.

See also: Wegovy vs. Zepbound

Z

Zepbound Medications

Eli Lilly's brand name for tirzepatide approved for weight management (and, more recently, for obstructive sleep apnea), given as a weekly injection. It shares its active ingredient with Mounjaro but carries the weight-loss label. In head-to-head trial data it produced greater average weight loss than Wegovy, making the two the headline rivalry in the category.

See also: Wegovy vs. Zepbound