FDA labels and the ADA Standards of Care spell out which labs belong at baseline, during titration, and at steady state on a GLP-1. Few patients leave the prescribing visit with that schedule written down. This card pulls the recommended panel, the frequency, and the action thresholds onto one page so you can compare what you're being offered to what's standard.
Baseline panel before the first dose
| Test | Why it matters | Source |
|---|---|---|
| HbA1c | Establishes diabetes vs. prediabetes vs. normoglycemia; sets the target for titration and the starting point for response. | ADA Standards of Care 2025 Section 6 (Glycemic Goals) |
| Fasting glucose | Identifies hypoglycemia risk if insulin or sulfonylureas are on board; gives a fasting comparator to A1C. | ADA Standards of Care 2025 Section 2 |
| Lipid panel (total, LDL, HDL, triglycerides) | GLP-1s lower triglycerides ~15-20% and LDL modestly; a baseline lets you separate drug effect from lifestyle effect later. | ADA Standards of Care 2025 Section 10 (Cardiovascular Disease) |
| Hepatic function panel (ALT, AST, alk phos, bilirubin) | Steatotic liver disease is common in the GLP-1 population; baseline AST/ALT lets you interpret any rise during titration. | AASLD 2023 MASLD Practice Guidance |
| Serum creatinine + eGFR | Volume depletion from nausea, vomiting, or diarrhea is the dominant renal risk on GLP-1s; you need a starting eGFR to detect a meaningful drop. | DailyMed Ozempic, Wegovy, Zepbound, Mounjaro labels Section 5 (Acute Kidney Injury) |
| TSH | Hypothyroidism mimics weight-loss resistance; treating it first avoids attributing a plateau to the GLP-1. | ATA 2014 Hypothyroidism Guidelines |
| Calcitonin — only if personal or family MTC history (otherwise skip) | Not a screening test in the general population. Predictive value is low without a thyroid nodule or family history of medullary thyroid cancer or MEN 2. | ATA 2015 Medullary Thyroid Cancer Guidelines; DailyMed Wegovy boxed warning |
| Vitamin B12 — especially if also on metformin | Metformin lowers B12 in 10-30% of long-term users; appetite reduction on a GLP-1 compounds the risk and makes neuropathy harder to distinguish. | ADA Standards of Care 2025 Section 9 (Pharmacologic Approaches) |
Titration phase — weeks 1 through about 20
- Week 4 clinical check-in. No labs required by label, but a tolerance review (nausea, vomiting, dehydration, hypoglycemia symptoms) and a blood-pressure check. Adjust insulin or sulfonylurea doses if fasting glucose is trending into the 70s.
- Week 12 HbA1c recheck (if on a GLP-1 for diabetes). The ADA expects a measurable A1C drop within 3 months; a flat A1C with adequate titration is the trigger to reassess adherence, dose, or diagnosis.
- Hepatic function only if symptomatic. New right-upper-quadrant pain, jaundice, or persistent nausea past week 4 warrants ALT, AST, lipase, and gallbladder imaging. Routine repeat LFTs during titration are not required by any GLP-1 label.
- eGFR if dehydration was severe. Repeat creatinine 1-2 weeks after any episode of vomiting or diarrhea that required oral rehydration or an ER visit.
- Pregnancy test before each dose escalation in patients of reproductive potential. Animal studies showed fetal harm; the Zepbound label adds that oral contraceptives may be less effective for 4 weeks after each titration step.
- Lipase or amylase only if pancreatitis is on the differential. Persistent severe abdominal pain radiating to the back. Routine pancreatic-enzyme screening is not indicated — see the next section.
Steady-state monitoring (maintenance dose)
- HbA1c every 3 months until at goal, then every 6 months. Per ADA Standards of Care 2025, Section 6.
- Lipid panel annually. More often only if starting or changing a statin.
- Hepatic function panel annually. More often only in MASLD or with new GI symptoms.
- Creatinine + eGFR annually. Every 3-6 months if eGFR is under 60 or the patient is on an ACE inhibitor, ARB, or diuretic.
- TSH only if symptomatic. Fatigue, cold intolerance, or unexplained plateau warrants a recheck; routine annual TSH is not required in patients with a normal baseline.
- B12 every 1-2 years in patients also on metformin. Sooner with new paresthesias or anemia.
- Calcitonin — no routine recheck. The boxed warning rests on counseling and palpation, not surveillance labs.
What not to routinely test
- Lipase and amylase as screening. False-positive rate is high in asymptomatic patients and a mild elevation does not predict pancreatitis. The DailyMed labels direct testing only when clinical signs are present.
- Calcitonin as a screen. Low positive predictive value in the absence of MTC family history or a thyroid nodule; expert societies do not endorse it as routine surveillance on GLP-1 therapy.
- Tumor markers (CEA, CA 19-9, CA 125). No evidence-based indication. Ordering them for GLP-1 surveillance generates costly workups for false positives.
- Body-composition DEXA on a fixed schedule. Useful in research and selected high-risk patients, not a class-wide recommendation.
Red-flag results — act, don't watch
- ALT or AST above 3× the upper limit of normal. Hold the dose, repeat in 1-2 weeks, work up other causes (alcohol, acetaminophen, viral, drug-induced).
- Creatinine rise greater than 25% from baseline (or eGFR drop into a new CKD stage). Hold the next dose, rehydrate, review NSAIDs and ACE/ARB doses, recheck in 1-2 weeks.
- Fasting glucose under 70 mg/dL or any symptomatic hypoglycemia on insulin or a sulfonylurea. Cut the insulin or sulfonylurea by 20-50%, not the GLP-1.
- Unexplained weight gain or A1C rise during steady-state therapy. Confirm adherence (storage, missed doses, pen technique) before assuming a true plateau; check TSH if symptomatic.
- Lipase greater than 3× ULN with abdominal pain radiating to the back. Discontinue, image for pancreatitis, do not restart until cleared.
What this cheat sheet does not cover
Type 1 diabetes monitoring (DKA risk, ketone testing, and continuous-glucose-monitor cadence) is not addressed here — FDA-approved GLP-1s are not indicated for type 1. Pediatric monitoring follows Wegovy and Saxenda product-specific labels in patients 12 and older and adds growth, puberty, and depression screening. Pre-bariatric or post-bariatric monitoring schedules belong to ASMBS protocols and overlap only partially with this card.
Related on Weight Loss Rankings
- All cheat sheets — the full one-page reference library.
- GLP-1 + Diabetes Medication Interactions — how to adjust insulin and sulfonylureas when fasting glucose drops.
- GLP-1 Sick-Day Guide — when dehydration during a stomach bug should trigger a creatinine recheck.
- GLP-1 Contraindications & Cautions — the MTC/MEN 2 boxed warning and the relative-contraindication list.
Sources
- American Diabetes Association. Standards of Care in Diabetes—2025. Diabetes Care 2025;48(Suppl. 1). Section 2 (Diagnosis), Section 6 (Glycemic Goals and Hypoglycemia, A1C every 3 months until at goal then every 6 months), Section 9 (Pharmacologic Approaches, metformin-related B12 deficiency), Section 10 (Cardiovascular Disease and Risk Management, annual lipid panel).
- DailyMed. WEGOVY (semaglutide) injection prescribing information. SetID ee06186f-2aa3-4990-a760-757579d8f77b. Boxed Warning (thyroid C-cell tumors), Section 5 (acute kidney injury, hypersensitivity, hypoglycemia with insulin/sulfonylurea, gallbladder), Section 8.1 (pregnancy).
- DailyMed. ZEPBOUND (tirzepatide) injection prescribing information. SetID 487cd7e7-434c-4925-99fa-aa80b1cc776b. Section 5 (acute kidney injury, acute gallbladder disease, pancreatitis), Section 7.1 (oral hormonal contraceptive effectiveness during initiation and dose escalation).
- DailyMed. OZEMPIC (semaglutide) injection prescribing information. SetID adec4fd2-6858-4c99-91d4-531f5f2a2d79. Section 5.4 (acute kidney injury), Section 5.5 (diabetic retinopathy complications), no routine lipase or amylase surveillance recommended.
- Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology 2023;77:1797-1835. Baseline and follow-up ALT/AST monitoring in metabolic-disease populations.
- Wells SA Jr, Asa SL, Dralle H, et al. Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma. Thyroid 2015;25:567-610. Calcitonin screening is not recommended in patients without MTC family history or a thyroid nodule.