GLP-1 Protocol8 min readApril 2026

What blood tests should you get before starting GLP-1?

Standard pre-prescription bloodwork checks 12–15 markers and flags pathology. Before starting semaglutide or tirzepatide, you need 8 specific biomarkers that most GLP-1 programmes never order — because they determine your protocol, predict your side effects, and set your baseline for measuring real progress.

Reviewed by WellSpry Medical Team · Board-certified physicians · View credentials →
Key Takeaways
→Standard pre-GLP-1 bloodwork (glucose + HbA1c) misses the biomarkers that matter most
→Fasting insulin reveals insulin resistance years before glucose rises — critical for dosing decisions
→Low testosterone dramatically increases lean mass loss during GLP-1 therapy
→Gut microbiome score below 5.0 predicts more severe nausea — address before starting
→The full panel takes 3–5 days and costs $399 through WellSpry, including physician interpretation

Most GLP-1 telehealth programmes send you a prescription within 24 hours of a five-question intake form. They check whether you qualify — BMI threshold, no contraindications — and that's it. What they never check is the information that actually determines how your protocol should be designed, which side effects you're likely to experience, and whether you'll lose muscle or fat.

Here are the 8 biomarker categories that should be tested before starting any GLP-1 therapy — and what each result means for your protocol.

01

HbA1c + Fasting Insulin

Your metabolic baseline

HbA1c alone misses early insulin resistance. Fasting insulin reveals the dysfunction years before glucose rises. A patient with HbA1c of 5.4% and fasting insulin of 22 μIU/mL has significant insulin resistance that standard testing would call normal.

02

ApoB

True cardiovascular risk

LDL cholesterol is calculated and frequently inaccurate. ApoB measures the actual number of atherogenic particles. GLP-1 therapy significantly reduces ApoB — knowing your baseline lets you track this benefit and inform Wegovy's cardiovascular indication for high-risk patients.

03

hs-CRP

Inflammatory load

GLP-1 has meaningful anti-inflammatory effects. hs-CRP above 3 mg/L suggests systemic inflammation that affects both response to GLP-1 and which supplements your physician will recommend (omega-3, curcumin, etc.). This is one of the most protocol-defining biomarkers.

04

Total + Free Testosterone

Muscle preservation risk

Low testosterone dramatically increases lean mass loss during caloric restriction. Men on GLP-1 with low-normal testosterone lose significantly more muscle. Women with testosterone below the low-normal range have similar issues with body composition. This drives the decision to introduce CJC-1295/Ipamorelin at month 3.

05

Thyroid Panel (TSH, Free T3, T4)

Metabolic rate baseline

Undetected hypothyroidism causes treatment-resistant weight loss. GLP-1 efficacy is reduced in the setting of untreated thyroid dysfunction. Subclinical hypothyroidism — TSH 2.5–4.5, normal T4 — is common and frequently undertreated.

06

Vitamin D (25-OH)

Deficiency worsens GI side effects

Vitamin D deficiency is found in approximately 40% of adults and is significantly more common in patients with obesity. Low D3 worsens nausea, fatigue, and mood changes during GLP-1 initiation. Correcting this before starting reduces side effect burden.

07

Gut Microbiome (BIOHM)

GI side effect prediction

Gut diversity score below 5.0 strongly predicts more severe GLP-1 nausea and GI side effects. Candida overgrowth — measurable only with fungal sequencing — worsens motility issues. Addressing dysbiosis before starting GLP-1 reduces the dropout rate in months 1–3.

08

Cortisol AM

Stress axis and fat distribution

Elevated cortisol (above 20 μg/dL AM) drives visceral fat accumulation that is more resistant to GLP-1 therapy. High cortisol also increases the risk of lean mass loss. This informs both the workout protocol design and supplement recommendations.

Get all 8 tested — plus 92 more — for $399.

WellSpry's Metabolic Intelligence Package includes all pre-GLP-1 biomarkers, gut microbiome analysis, physician interpretation, and your personalised protocol. Kit ships next day. HSA/FSA eligible.

Get My Testing Kit — $399 →

Frequently Asked Questions

What blood tests should I get before starting GLP-1?

Before starting GLP-1 therapy, you should test: HbA1c and fasting insulin (to establish your metabolic baseline), ApoB and hs-CRP (cardiovascular and inflammatory risk), testosterone (muscle preservation risk), thyroid panel (TSH, Free T3, T4), vitamin D and B12 (deficiencies worsen GLP-1 side effects), liver panel (ALT, AST, GGT), and a gut microbiome analysis (dysbiosis worsens GI side effects). Standard pre-prescription bloodwork — just glucose and HbA1c — misses most of what matters.

Does insurance cover blood tests before GLP-1?

Physician-ordered diagnostic testing is HSA and FSA eligible regardless of whether commercial insurance covers it. WellSpry's $399 testing package covers all pre-GLP-1 biomarkers and is HSA/FSA eligible. For a patient in the 32% tax bracket, the effective cost is approximately $271.

What is the most important blood test before starting Wegovy or Zepbound?

The most clinically important pre-GLP-1 test is fasting insulin, followed by ApoB. Fasting insulin reveals insulin resistance that standard HbA1c misses in early stages. ApoB is the most accurate predictor of cardiovascular risk and determines whether aggressive treatment is appropriate. Both are absent from most standard pre-prescription panels.