Do You Need Labs Before Starting a GLP-1 Medication?

Short answer: the FDA doesn't mandate a GLP-1-specific lab panel before starting Wegovy, Zepbound, or Foundayo — but that doesn't mean labs never matter.^[1][2][3]Clinical guidance, including the AACE 2025 obesity/ABCD algorithm, still recommends a cardiometabolic baseline assessment, and a provider skipping indicated labs isn't necessarily following best practice just because no label checklist requires them.^[4]

If you're comparing providers and notice some require bloodwork before prescribing while others don't, this explains what's actually behind that difference — what the FDA does and doesn't mandate, what clinical guidelines recommend regardless, and why the distinction matters for your safety, not just as a procedural hoop to jump through.

What the FDA Actually Requires: Less Than You Might Think

Here's something that surprises a lot of people: the prescribing information for Wegovy, Zepbound, and Foundayo lists indications, dosing, contraindications, and warnings in detail — but none of them specify a mandatory lab panel that must be completed before starting treatment.^[1][2][3] The FDA leaves that decision to clinical judgment, guided by relevant disease-specific guidelines (like diabetes or cardiovascular risk management), rather than setting a GLP-1-specific lab requirement.

This is an important distinction to understand: "not FDA-required" doesn't mean "not recommended."It means the FDA isn't the body making this particular call — professional medical societies are, and they've been fairly consistent about what they recommend.

What Clinical Guidelines Actually Recommend

The AACE 2025 consensus algorithm for adults with obesity/ABCD recommends a cardiometabolic baseline panel — not a single three-test mandate identical across every society, but a clearer recommended set than "whatever feels optional."^[4] That recommended assessment typically includes serum creatinine (eGFR), a lipid panel, fasting glucose, HbA1c, and AST/ALT plus platelet count (to support FIB-4 liver-fibrosis risk scoring), with broader general-health labs (such as CBC or a full CMP) added when clinically appropriate.^[4]

Comprehensive Metabolic Panel (CMP)

This checks kidney function (creatinine and eGFR), electrolytes, and baseline blood sugar. It matters specifically because GLP-1 medications can cause gastrointestinal side effects that lead to dehydration, and dehydration can affect kidney function — having a baseline makes it possible to tell whether kidney values have shifted during treatment, and why.^[1][2][4]

HbA1c (A1C)

AACE includes A1C in the recommended cardiometabolic baseline set.^[4] It documents your baseline blood sugar control over the past several months, helps confirm or rule out diabetes or prediabetes, and establishes a marker your provider can recheck later if glucose status or diabetes care goals make follow-up testing relevant.

Fasting Lipid Panel

AACE also includes lipids in that baseline cardiometabolic assessment.^[4]This checks cholesterol and triglycerides both to document baseline cardiovascular risk and because GLP-1 medications often improve these numbers — having a starting point lets you and your provider actually see and track that improvement, not just assume it's happening.

Liver Function Tests

AACE recommends AST, ALT, and platelet count as part of baseline assessment so FIB-4 can be calculated when appropriate — particularly useful if there's concern for metabolic dysfunction–associated liver disease.^[4] Baseline liver values also help identify pre-existing issues and provide context if anything changes during treatment.

Thyroid Function (TSH)

TSH is not a universal MTC screen. AACE frames thyroid testing as something to order when clinically indicated, not as blanket calcitonin or ultrasound screening for every GLP-1 starter.^[4] And the Wegovy, Zepbound, and Foundayo labels are explicit that the value of routine serum calcitonin or thyroid ultrasound for early medullary thyroid carcinoma detection is uncertain.^[1][2][3]What TSH can do is flag other thyroid conditions when they're relevant; the MTC/MEN2 risk conversation still runs primarily through personal and family history questions, not a TSH result.

Additional Tests, Depending on Your Situation

• Complete blood count (CBC) — not universal, but sometimes used as a general-health lab or to calculate certain liver-related risk scores when indicated.^[4]
• Urine albumin-to-creatinine ratio — sometimes used in people with diabetes to assess kidney health more specifically
• A retinal (eye) exam — relevant for people with type 2 diabetes and preexisting diabetic retinopathy (especially on semaglutide), because rapid glycemic improvement can temporarily worsen retinopathy in that setting — not a routine eye exam for every GLP-1 starter without diabetes or retinopathy history.^[1]

Why This Matters More Than It Might Seem

It would be easy to read a list of lab tests and think of it as bureaucratic box-checking. It isn't. Each of these tests exists to catch something that could meaningfully change whether — or how — you should be treated:

• Undiagnosed diabetes or prediabetes would change the treatment conversation entirely
• Unrecognized kidney disease matters directly, since these medications carry a real risk of kidney strain if dehydration from GI side effects goes unmanaged
• Undetected liver disease is relevant given the (rare) hepatic and gallbladder-related events associated with this drug class
• A missed personal or family history relevant to thyroid cancer risk is directly tied to the most serious warning these medications carry

A provider skipping all of this isn't necessarily doing anything illegal — but they are skipping a step that professional medical guidance consistently recommends, and that omission is worth knowing about and factoring into your decision, not something you'd necessarily notice was missing on your own.

What Monitoring Looks Like After You Start

Getting baseline labs is only part of the picture — ongoing monitoring while on treatment follows a similar "guided by clinical context, not mandated by the drug" pattern.

What gets rechecked after you start depends heavily on whether you have diabetes and on your other cardiometabolic risks — not on a single GLP-1 label schedule for everyone:

• HbA1c every ~3 months until goals are met (then about every 6 months) is a standard diabetes-caremonitoring pattern, not a universal obesity-drug requirement for people without diabetes. If you don't have diabetes, your provider may recheck glucose/A1C less often or mainly when clinically indicated.^[4]
• Annual kidney function testing for anyone with diabetes
• Periodic lipid panels, often annually or per general cardiovascular guidelines.^[4]

Beyond this baseline schedule, additional labs are typically ordered only when something specific comes up — pancreatic enzyme testing if pancreatitis is suspected, liver testing or imaging if gallbladder symptoms appear, or thyroid evaluation if relevant symptoms or family history surface during treatment.^[1][2] Weight, BMI, waist circumference, and blood pressure are generally tracked at each visit regardless of lab schedule, since these are the most direct measures of how treatment is progressing.^[4]

What This Means for Telehealth Specifically

Telehealth prescribing guidance is explicit on this point: remote care is supposed to meet the same clinical standard as in-person care, including ordering labs when clinically indicated — not skipping them simply because the visit happens over video instead of in an exam room.^[5]Labs can be coordinated through a local lab facility even when the visit itself is virtual, so "telehealth" and "no labs required" aren't the same thing, even though some providers structure their offerings that way.

Professional guidance is fairly direct that prescribing GLP-1 medications with zero baseline labs risks missing undiagnosed diabetes, kidney disease, or liver disease — and that skipping this step generally isn't considered best practice, regardless of whether the visit was virtual or in-person.^[4][5]

What to Ask When Comparing Providers

Given how much this varies between providers, it's worth asking directly:

• Does this provider require any baseline labs, or can you start with none at all?
• If labs are required, are they included in the price, or an additional cost?
• Can you use existing recent labs from another provider, or does everything need to be redone?
• What's the process if a lab result comes back outside a normal range?

None of these questions have a universally "right" answer — a provider requiring more testing isn't automatically better, and one requiring less isn't automatically cutting corners — but understanding what's actually being checked (or not checked) is part of making an informed choice.

Frequently Asked Questions

See also: How to Get Prescribed a GLP-1 Medication for the full evaluation and prescription process, and Who Qualifies for GLP-1 Medications? for the complete contraindications and candidacy criteria.