DPDaily Peptide

SEMAGLUTIDE · DECODED

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FDA APPROVEDGLP-1 RECEPTOR AGONIST

Semaglutide

Decoded · Novo Nordisk · FDA Approved

The molecule that proved the category. Before semaglutide, GLP-1 therapy was a niche diabetes treatment. After the STEP trials and SELECT, it became the most consequential obesity drug ever approved, and the reference point every GLP-1 that follows is measured against.

BY THE NUMBERS

14.9%
AVG BODY WEIGHT LOSS · STEP 1 · 68 WK
20%
REDUCTION IN MAJOR CARDIAC EVENTS · SELECT TRIAL
3
FDA-APPROVED FORMULATIONS · OZEMPIC · WEGOVY · RYBELSUS
70%+
PATIENTS ACHIEVED ≥5% WEIGHT LOSS · STEP 1

HOW IT WORKS

GLP-1 receptor agonist. Mimics the endogenous incretin hormone GLP-1, suppressing appetite, slowing gastric emptying, reducing glucagon secretion, and increasing glucose-dependent insulin release. A C18 fatty acid chain binds albumin in circulation, extending the half-life to approximately 7 days and enabling once-weekly dosing.

WHERE IT CAME FROM

Semaglutide is a glucagon-like peptide-1 receptor agonist developed by Novo Nordisk. GLP-1 is a hormone naturally released by the gut after eating. It signals the pancreas to release insulin, signals the liver to stop releasing excess glucose, slows gastric emptying, and tells the brain that the body has had enough to eat. Semaglutide mimics this hormone with a critical structural difference: the natural version breaks down within minutes. Semaglutide lasts a week.

The extended half-life comes from a modification that binds semaglutide tightly to albumin, a protein in the blood, shielding it from the enzymes that would otherwise degrade it rapidly. That modification is what makes once-weekly dosing possible. Novo Nordisk first received FDA approval for semaglutide under the brand name Ozempic in 2017, indicated for type 2 diabetes. Approval for chronic weight management under the brand name Wegovy followed in 2021 at a higher dose. An oral tablet formulation, Rybelsus, received separate approval in 2019 for type 2 diabetes.

THE STUDIES

2017
SUSTAIN program (T2D): SUSTAIN was Novo Nordisk's eight-trial Phase 3 program designed to establish semaglutide's effectiveness in type 2 diabetes. The trials compared semaglutide against insulin and other diabetes drugs across thousands of patients. Semaglutide came out superior on both blood sugar reduction and weight loss in every major comparison.
2021
STEP 1 (NEJM): STEP 1 was the landmark Phase 3 trial that tested semaglutide specifically for weight loss in people with obesity who did not have diabetes. 1,961 adults were enrolled and followed for 68 weeks. Those on 2.4 mg weekly semaglutide lost an average of 14.9% of body weight versus 2.4% on placebo. 35% of participants lost at least 20% of body weight. Source: Wilding et al., NEJM 2021, PMID 33567185.
2022
STEP 4 (JAMA): STEP 4 tested what happens when patients who lost weight on semaglutide stop taking it. After 20 weeks of successful weight loss on the drug, half the group was switched to placebo for the remaining 48 weeks. Those who stopped regained two-thirds of the weight they had lost within a year, establishing clearly that the benefit requires ongoing treatment.
2023
SELECT (NEJM): SELECT was a cardiovascular outcomes trial, meaning its primary goal was not weight loss but rather whether semaglutide could reduce serious heart events. It enrolled 17,604 overweight or obese adults who had established cardiovascular disease but no diabetes. Semaglutide reduced heart attacks, strokes, and cardiovascular deaths by 20% versus placebo. It was the first GLP-1 receptor agonist to demonstrate this benefit in a population without type 2 diabetes.

WHAT THE STUDIES SHOW

WEIGHT LOSS

  • ▸14.9% avg weight loss (STEP 1, 68 wk)
  • ▸35% of patients lost ≥20% body weight
  • ▸70%+ achieved ≥5% weight loss
  • ▸Weight regains substantially after stopping

CARDIOMETABOLIC

  • ▸20% reduction in major cardiac events (SELECT trial)
  • ▸Blood sugar (HbA1c) reduction in type 2 diabetes
  • ▸Systolic blood pressure reduction
  • ▸Triglyceride and LDL improvement

EMERGING SIGNALS

  • ▸Metabolic liver disease (MASH) benefit in early data
  • ▸Addiction and craving reduction signals
  • ▸Kidney disease progression signals
  • ▸Dementia risk reduction signals (early, preliminary)

SIDE EFFECTS

COMMON (TITRATION PHASE)

  • ▸Nausea (~44% in STEP trials)
  • ▸Diarrhea (~30%)
  • ▸Vomiting and constipation
  • ▸Abdominal pain and bloating
  • ▸Most improve as the body adjusts over weeks

NOTABLE / LESS COMMON

  • ▸Gallbladder disease, including gallstones
  • ▸Pancreatitis (rare, monitor for symptoms)
  • ▸Thyroid C-cell tumors in rodent studies (human relevance unknown)
  • ▸Injection site reactions
  • ▸Hypoglycemia risk when combined with insulin or sulfonylureas

REGULATORY STATUS

FDA STATUS
FDA Approved · Ozempic (2017) · Wegovy (2021) · Rybelsus (2019)
PHASE
Approved · Post-market surveillance
PROJECTED NDA
N/A · Already approved

Semaglutide holds three distinct FDA approvals. Ozempic is approved for type 2 diabetes management and cardiovascular risk reduction in adults with established cardiovascular disease. Wegovy is approved for chronic weight management in adults with obesity or overweight with at least one weight-related condition. Rybelsus, the oral formulation, is approved for type 2 diabetes. Each carries specific labeled indications; use outside those indications is off-label. Compounded semaglutide was available through state-licensed 503A pharmacies filling individual prescriptions and FDA-registered 503B outsourcing facilities during a documented shortage period. That shortage status shifted through 2024 and 2025 as brand supply stabilized, with significant ongoing regulatory activity around compounding eligibility.

PROS & CONS

PROS

  • +Most studied GLP-1 in the class, with the deepest long-term safety record
  • +FDA approved for both obesity and type 2 diabetes
  • +Proven 20% cardiovascular event reduction in non-diabetic population (SELECT)
  • +Oral formulation available (Rybelsus) for those who prefer not to inject
  • +Once-weekly injectable dosing
  • +Broadest insurance coverage of any GLP-1

CONS

  • −Lower weight loss ceiling than tirzepatide or retatrutide
  • −GI side effects common, particularly during titration
  • −Weight regain is significant and rapid after stopping
  • −Thyroid and gallbladder risks require monitoring
  • −List price high without insurance coverage
  • −Compounding availability has narrowed as shortage designation has shifted

DAILY PEPTIDE VERDICT

RANKING

The Reference Point

Semaglutide is the molecule that changed the conversation. Before Ozempic, weight loss pharmacotherapy was a niche category with modest results and limited mainstream evidence. The STEP trials delivered 15% average weight loss across a broad population. The SELECT trial added a cardiovascular benefit that most weight loss drugs have never demonstrated in any population. Newer agents, tirzepatide and retatrutide among them, have since produced higher weight loss figures. Semaglutide's combination of trial depth, safety record built across millions of patients over nearly a decade, and prescribing volume makes it the most documented compound in the class.

Also in WEIGHT LOSS

// WEIGHT LOSS

Tirzepatide

FDA APPROVEDPHASE 3+

// WEIGHT LOSS

Retatrutide

INVESTIGATIONALPHASE 3+

DISCLAIMER · EDUCATIONAL USE ONLY

This document is for educational and informational purposes only. Semaglutide is an FDA-approved pharmaceutical. Prescribing, dosing, and clinical application are the purview of a licensed healthcare provider. Information here synthesizes publicly available clinical data and does not constitute medical advice.