Last reviewed: June 20, 2026
Last updated: June 20, 2026
Written by:
Jay Hastings,
CEO of PlexusDx
Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance.
Medically reviewed by:
Jayden Lee, PharmD, EMBA
Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.
This article is part of the PlexusDx Education Hub — science-backed guidance on GLP-1 medications, metabolic health, and precision weight management.
The SELECT trial, published in 2023, tracked over 17,500 adults with obesity and cardiovascular disease who received either semaglutide or placebo. Results showed that semaglutide reduced the risk of major adverse cardiovascular events (MACE) by 20 percent, marking a significant finding for people considering weight loss medications. This landmark study extends beyond weight management alone, revealing how GLP-1 receptor agonists may protect heart health.
What the SELECT Trial Discovered About Semaglutide Safety
The SELECT trial enrolled adults aged 45 and older with established cardiovascular disease or significant cardiovascular risk factors. Participants received weekly semaglutide injections up to 2.4 mg or placebo over approximately 2 years of follow-up. The study found that semaglutide reduced MACE—a combined endpoint of heart attack, stroke, and cardiovascular death—by 20 percent compared to placebo, regardless of how much weight participants lost.
This cardiovascular benefit emerged even among people who did not achieve large weight reductions, suggesting semaglutide's heart-protective effects operate through multiple mechanisms beyond weight loss alone. Researchers observed improvements in blood pressure, inflammation markers, and other cardiometabolic factors in the semaglutide group. These findings reassured clinicians and patients that semaglutide offers benefits beyond the scale.
How SELECT Results Apply to Your Weight Loss Decision
If you have obesity and existing heart disease or significant cardiovascular risk factors, the SELECT trial provides evidence that semaglutide therapy may lower your cardiovascular event risk while supporting weight management. The trial included diverse participants across multiple countries and healthcare settings, making results broadly applicable to many populations. Your personal risk profile, medical history, and treatment goals should guide whether semaglutide aligns with your health plan.
PlexusDx offers compounded semaglutide injections starting at $149 per month through licensed 503A pharmacies, making this evidence-based therapy accessible without insurance requirements. A healthcare provider consultation determines whether semaglutide suits your individual situation and what starting dose is appropriate for your treatment plan. The Precision Peptide Genetic Test ($99 add-on) can identify genetic factors influencing your GLP-1 receptor pathway response, helping personalize your therapy approach.
Understanding SELECT Trial Side Effects and Tolerability
The SELECT trial documented gastrointestinal side effects like nausea, vomiting, and diarrhea in the semaglutide group, consistent with known GLP-1 receptor agonist profiles. Most side effects were mild to moderate and declined over time as the body adapted to treatment. Only a small percentage of participants discontinued semaglutide due to adverse events, indicating good overall tolerability across the study population.
Serious adverse events occurred at similar rates between semaglutide and placebo groups, suggesting semaglutide did not introduce unexpected safety concerns in this population. Individual tolerance varies—some people experience minimal side effects while others need dose adjustments or timing modifications. Working with a healthcare provider allows monitoring and managing any side effects that develop during your treatment course.
SELECT Trial Implications for Personalized GLP-1 Therapy
The SELECT trial reinforces that semaglutide's benefits extend to people with cardiovascular disease and obesity, moving treatment beyond purely cosmetic weight loss goals. However, individual responses to semaglutide vary significantly based on genetic factors, lifestyle, concurrent medications, and metabolic characteristics. Genetic variants in the GLP1R gene (like rs6923761) and GIPR gene (rs1800437) influence how effectively your body responds to GLP-1 therapy.
PlexusDx's Precision Peptide Genetic Test maps 14 metabolic pathways and analyzes 150+ genetic insights related to peptide responses, helping identify whether you might benefit most from semaglutide, tirzepatide, combination therapy, or microdose protocols. Testing occurs after starting treatment and costs $99 as an add-on, allowing data-driven dose and medication adjustments based on your genetic predispositions. This personalization approach aligns with SELECT trial findings that individual variation in response is substantial and measurable.
How Your Genetics Influence GLP-1 Response
Not everyone responds to GLP-1 medications the same way. Genetic variants — including GIPR rs1800437, GLP1R rs6923761, FTO rs9939609, and MC4R rs17782313 — influence how your body processes these medications, how much weight you lose, and how you tolerate side effects. PlexusDx maps 14 pathways, 49 peptides, and 150+ genetic insights to match each patient to the right medication, dose, and lifestyle protocol for their biology. The PlexusDx Precision Peptide Genetic Test ($99 add-on after your first month of treatment) gives your provider precise insight into your peptide genetic predispositions before the first prescription is written.
Access Personalized GLP-1 Care Through PlexusDx
PlexusDx offers six prescription GLP-1 protocols to all 50 states — no membership, no insurance required, async intake or live consult. The Semaglutide Injection starts at $149/mo. Medications are dispensed from licensed 503A compounding pharmacies following strict quality and safety standards. Add a Precision Peptide Genetic Test for $99 to personalize your protocol from day one.
Frequently Asked Questions
Does the SELECT trial mean everyone with obesity should take semaglutide?
No—SELECT enrolled adults aged 45+ with established cardiovascular disease or high cardiovascular risk. Your individual health status, medications, and medical history determine whether semaglutide is appropriate. A healthcare provider should evaluate your specific situation before starting any GLP-1 therapy.
How much weight did SELECT trial participants lose on semaglutide?
The SELECT trial focused on cardiovascular outcomes rather than weight loss as the primary measure. Participants who received semaglutide experienced average weight reductions, though the cardiovascular benefits observed occurred independent of weight loss magnitude, suggesting multiple protective mechanisms at work.
Is compounded semaglutide from PlexusDx the same medication studied in SELECT?
PlexusDx semaglutide injections contain the same active pharmaceutical ingredient (semaglutide) as branded Ozempic, compounded by licensed 503A pharmacies. PlexusDx starts at $149 per month without insurance requirements, making this evidence-based therapy more accessible than branded alternatives.
What percentage of people experienced side effects in the SELECT trial?
Gastrointestinal side effects like nausea occurred in a significant portion of the semaglutide group but were typically mild to moderate and decreased over time. Serious adverse events occurred at similar rates between semaglutide and placebo, indicating that side effects were manageable rather than dangerous for most participants.
Can PlexusDx Precision Peptide Genetic Testing predict my SELECT trial-like outcomes?
The Precision Peptide Genetic Test ($99) identifies variants in GLP1R, GIPR, FTO, and MC4R genes that influence your peptide pathway responses and medication effectiveness. This personalized data helps determine whether semaglutide, tirzepatide, or combination therapy aligns with your genetic predispositions, optimizing outcomes beyond population averages.
Related Reading
Pricing and availability current as of June 2026. Compounded GLP-1 medications are not FDA-approved drug products; they are prepared by licensed compounding pharmacies under federal compounding regulations. Compounded semaglutide and tirzepatide are not the same as Wegovy, Ozempic, Zepbound, or Mounjaro. This article is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting, stopping, or changing any medication.
Return to the PlexusDx Education Hub for more evidence-based resources on GLP-1 therapy, metabolic health, and personalized weight management.
Medical and Editorial Standards
Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.
Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance.
Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.
Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.
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