What Labs Should You Get Before Starting a GLP-1? Baseline Bloodwork, Explained
Starting semaglutide, tirzepatide, or another GLP-1 medication is a big step — and one that works best with a clear "before" picture. Whether your prescription comes from a telehealth provider, a weight-loss clinic, or your own doctor, baseline lab work is the part of the process that too often gets skipped. Here's what providers typically check before you start a GLP-1, why each test matters, and how to get it done quickly without a doctor's visit.
Why Baseline Labs Matter Before a GLP-1
GLP-1 medications change how your body handles blood sugar, appetite, and digestion. That's the point — but it also means your metabolic numbers are about to move. Baseline bloodwork does three things:
- Establishes your starting point: You can't measure progress you never recorded. A baseline A1c, lipid panel, and metabolic panel turn "I feel better" into numbers you and your provider can track.
- Catches issues before they matter: Kidney function, liver enzymes, and blood sugar problems are all things a provider wants to know about before prescribing — not after.
- Protects your access to the medication: Many telehealth prescribers require recent labs to start or continue therapy. Having them done keeps your treatment moving.
The Tests Providers Commonly Check
- Hemoglobin A1c: Your three-month average blood sugar. It documents where you started and helps distinguish weight-management use from diabetes management.
- Comprehensive Metabolic Panel (CMP): Covers fasting glucose, kidney function, electrolytes, and liver enzymes — the core safety check, since nausea and reduced intake on GLP-1s can affect hydration and kidneys.
- Lipid Panel: Cholesterol and triglycerides typically improve with weight loss; the baseline lets you see it happen.
- Thyroid check (TSH): Often included when fatigue or weight changes are part of the picture, and worth discussing with your provider given thyroid-related precautions on GLP-1 labels.
Some providers also look at a complete blood count (CBC) or vitamin levels, since eating substantially less can affect nutrition over time.
How Often Should You Recheck?
Most providers recommend a baseline before your first dose, then a recheck every 3 to 6 months while on therapy. Rechecks confirm the medication is doing its job — A1c and lipids improving — and that kidneys, liver, and electrolytes are staying in a healthy range as your intake changes. If you're losing weight quickly, your provider may want labs on the earlier end of that window.
Getting It Done Without a Doctor's Visit
Here's the frustrating part for many GLP-1 patients: your telehealth prescriber may ask for labs but not offer a convenient way to get them. That's exactly the gap our GLP-1 Monitoring Panel fills — it bundles the tests providers look at most into a single blood draw. Order online in minutes, visit a collection site near you (no appointment needed at most locations), and get results delivered privately, ready to share with your prescriber.
You can read more about how monitoring works throughout GLP-1 therapy on our GLP-1 Lab Monitoring page.
A Note on Safety
Lab testing supports your GLP-1 journey, but it doesn't replace medical supervision. Share your results with your prescribing provider, report side effects like severe stomach pain or persistent vomiting promptly, and never adjust your dose on your own. The combination of a good provider and regular bloodwork is what makes GLP-1 therapy both effective and safe.
Start With a Clear Baseline
If you're about to begin — or recently began — a GLP-1 medication, get your starting numbers on record. Order the GLP-1 Monitoring Panel today, and check out our guide to reading lab results when your numbers come back. Your future self — 20 pounds lighter and wondering how far you've come — will thank you for the "before" picture.
