Can taking semaglutide result in dangers to vision? This is an important question, as semaglutide is an active ingredient successfully used in the treatment of inadequately controlled type 2 diabetes mellitus to improve glycaemic control, in addition to a low-calorie diet and increased exercise.
When administered at a higher dosage in patients with obesity, semaglutide can allow significant weight loss.
It is a substance authorised by the FDA in the US and by the EMA in many European countries and in Italy. Three medicinal specialities are on the market: Ozempic®, Rybelsus®, Wegovy®
Semaglutide is an analogue of the hormone GLP-1 (glucagon-like peptide-1), a substance in our bodies that regulates glucose levels, modulates appetite and the cardiovascular system. Semaglutide has a similar 94% structure to human GLP-1 and acts on the same receptors by activating them. This mechanism of action leads to a reduction in blood glucose by stimulating insulin secretion, delays gastric emptying by reducing appetite, and lowers blood lipid levels, systolic blood pressure and inflammation.
This reduction in glycaemic level can affect vision, firstly because it can alter the shape of the crystalline lens, leading to blurred vision.
This side effect occurs particularly in elderly patients when they start taking the drug, as their crystalline lens is less flexible due to ageing and visual function consequently takes longer to stabilise when blood sugar concentrations change.
Fortunately, this is, in most cases, a temporary side effect, which tends to disappear within three to four months after starting therapy.
Furthermore, according to data from a study, published in August 2024 in Jama Ophthalmology "Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide" there may be a correlation between semaglutide and increased risk of severe visual impairment due to a serious eye disease, non-arteritic optic neuritis or NAION. The data and limitations of this study do not allow a causal correlation to be established and recommend discontinuation of the drug in diabetic patients, who are in any case at risk of NAION, regardless of the therapy they are taking. In this sense, the recommendation is to consider this experimental data and to base one's therapeutic choices on an accurate risk assessment for the individual patient.
The general rule must be that whatever hypoglycaemic therapy the patient with type 2 diabetes is taking, it is necessary in parallel to adopt a correct lifestyle, including a controlled and balanced diet and moderate and regular physical activity.
Semaglutide is not, however, indicated for patients with type 1 diabetes and for anyone who may develop diabetic ketoacidosis.
In patients with diabetic retinopathy, the addition of semaglutide to insulin may increase the risk of complications. In most cases, this increased risk is manageable and reversible. It is, therefore, of utmost importance that patients with diabetic retinopathy who are treated with semaglutide are regularly monitored by their ophthalmologist, who will be able to detect any drug-induced changes and take the necessary corrective action.
Researchers are meanwhile studying the long-term effects of semaglutide on patients with type 2 diabetes-related diabetic retinopathy. The study, called FOCUS, will evaluate the effects of semaglutide on diabetic retinopathy in combination with other diabetes drugs and is expected to end in February 2027.
On the subject of diabetes-related eye diseases see:
- Diabetes and the eye - Italian Ophthalmologist
- Type 2 diabetes and retinopathy: different phenotypes predict progression - Oculista Italiano
- Hathaway JT, Shah MP, Hathaway DB, et al. Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide. JAMA Ophthalmol. 2024 Aug 1;142(8):732-739. doi: 10.1001/jamaophthalmol.2024.2296. PMID: 38958939; PMCID: PMC11223051.
- Diabetes Control and Complications Trial (DCCT): Results of Feasibility Study. The DCCT Research Group. Diabetes Care1 January 1987; 10 (1): 1-19. https://doi.org/10.2337/diacare.10.1.1
- Smits MM, Van Raalte DH. Safety of semaglutide. Front Endocrinol (Lausanne). 2021;12:645563. doi:3389/fendo.2021.645563