Semaglutide: what the research shows

What semaglutide is

Semaglutide is an analogue of glucagon-like peptide-1 (GLP-1), a hormone released by the intestine, with an extended half-life of about one week. It acts as a GLP-1 receptor agonist and was developed by Novo Nordisk. [1] [3] [5]

Because it acts only on the GLP-1 receptor, semaglutide is the reference point against which newer multi-receptor molecules such as tirzepatide (GIP and GLP-1) and retatrutide (GIP, GLP-1 and glucagon) are compared; see our guides on those molecules.

How it has been studied

Semaglutide has been tested in large randomised, double-blind, placebo-controlled trials, all funded by Novo Nordisk: in type 2 diabetes (the SUSTAIN programme), in weight management (the STEP programme) and in cardiovascular outcomes in people without diabetes (SELECT). [1] [2] [3]

Safety findings reported so far

In STEP 1, nausea and diarrhoea were the most common adverse events; they were typically transient, mild to moderate, and subsided with time. More participants stopped treatment because of gastrointestinal events with semaglutide (4.5%) than with placebo (0.8%). [2]

In SUSTAIN-6, rates of new or worsening kidney disease were lower with semaglutide, but complications of diabetic retinopathy were significantly more frequent. In SELECT, adverse events led to permanent discontinuation in 16.6% of participants on semaglutide and 8.2% on placebo. [1] [3]

The prescribing information of the approved semaglutide medicine for weight management carries a boxed warning about the risk of thyroid C-cell tumours. [5]

Regulatory status and salt forms

Semaglutide is the active ingredient of prescription medicines approved in the United States. One of them is approved to reduce excess weight and maintain weight reduction in certain adults with obesity or overweight and, since 8 March 2024, to reduce the risk of cardiovascular death, heart attack and stroke in adults with cardiovascular disease and either obesity or overweight. [5]

The FDA notes that salt forms such as semaglutide sodium and semaglutide acetate are different active ingredients from the one used in the approved drugs, and that it has no information on whether they have the same chemical and pharmacological properties. [6]

The FDA has also warned companies that sold semaglutide, tirzepatide or retatrutide directly to consumers for human use, with dosing instructions, while labelling the products ‘for research purposes’ or ‘not for human consumption’. Research material is not a medicine: it has not been reviewed for safety, effectiveness or quality in people and must not be used in people. We sell semaglutide only for in vitro laboratory research, without instructions for use. [6]

Storage and stability in the lab

Peptides can degrade through chemical routes such as oxidation, deamidation and hydrolysis and through physical routes such as aggregation, and they are generally more stable in the dry state than in solution. [7]

Lyophilised vials are therefore normally kept cold, dry and away from light until they are reconstituted. The storage statement on the product page and on the batch certificate takes precedence.

How to check a batch

A useful certificate of analysis names the testing laboratory, the batch number printed on the vial, the test date and the methods used. Identity is usually confirmed by mass spectrometry, where the measured mass should match the expected molecular mass, and purity is measured by HPLC. For semaglutide it is also worth checking which form the batch is, base or a salt such as the acetate, since the measured mass and the amount of peptide per vial depend on it.

Where the manufacturer supplies a batch report, we link it on the product page; products without one do not claim one.