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Research roundup

Four new studies making headlines this month: a possible link between GLP-1s and hair loss, fresh evidence that the meningococcal B vaccine may also cut gonorrhoea risk, a glaucoma warning for men taking tadalafil long-term for urinary symptoms, and further confirmation that eczema raises the risk of shingles.

GLP-1s and hair loss
Glucagon-like peptide-1 agonists (GLP-1s) may increase the risk of non-scarring hair loss in adults with type 2 diabetes (T2D), an analysis of US health records reveals.
Researchers compared 12,004 T2D patients using GLP-1s with 15,221 receiving sodium-glucose co-transporter-2 (SGLT-2) inhibitors. They also compared 11,964 GLP-1 users with 11,233 T2D patients taking dipeptidyl peptidase-4 (DPP-4) inhibitors.
Adjusting for confounders, GLP-1s were associated with a 37% higher alopecia risk than SGLT-2 inhibitors (6.91 and 5.04 per 1,000 person-years respectively). GLP-1s were associated with a 68% higher risk than DPP-4 inhibitors (6.53 and 3.89 per 1,000 person-years respectively).
The risk was confined to non-scarring alopecia, where the hair follicles remain intact, so the hair may regrow. GLP-1s increased the likelihood of non-scarring alopecia in T2D patients by 53% and 72% compared with SGLT-2 inhibitors and DPP-4 inhibitors respectively.
Alopecia was most common during the year after starting treatment.
Rapid and marked weight loss can trigger telogen effluvium (diffuse non-scarring hair loss). Micronutrient deficiencies in, for example, biotin, iron and zinc, and hormonal changes may also contribute to the hair loss. Studies need to characterise the mechanisms, especially the effect of weight loss. The authors could not assess the alopecia’s severity, extent, duration and reversibility.
“Although the absolute risk is low, awareness of this potential effect may help to inform treatment decisions,” the authors comment.
BMJ doi: 10.1136/bmj-2026-100077
Meningococcal B vaccine cuts gonorrhoea risk
The meningococcal B (MenB) vaccine reduces the risk that young people will catch gonorrhoea, Australian researchers report.
“This study adds to growing evidence that the Men B vaccine may offer modest protection against gonorrhoea when provided to young people, in addition to its established role in preventing invasive meningococcal disease,” says principal investigator Professor Helen Marshall from Adelaide University.
The study enrolled 30,650 adolescents, aged, on average, 16.2 years. Two doses of the 4CMenB vaccine reduced the risk of gonorrhoea by 38.4% in those aged 14 to 22 years.
The MenB vaccine did not reduce the presence of disease-associated meningococcal bacteria in the throat over a year (carriage rates of 1.4–1.5%). In other words, the MenB vaccine directly protects people from group B meningococcal disease but does not reduce transmission between people.
The researchers did not have access to information about potentially important factors such as sexual behaviour, healthcare engagement, testing frequency and other immunosuppressive medications and diseases.
The bacteria that cause meningococcal disease and gonorrhoea are close relatives; the MenB vaccine appears to trigger immune responses that prevent both infections.
Open Forum Infectious Diseases DOI: 10.1093/ofid/ofag409
Tadalafil for lower urinary symptoms increases glaucoma risk
Tadalafil increases the risk of glaucoma among men using the phosphodiesterase type-5 inhibitor (PDE5i) for lower urinary tract symptoms (LUTS), according to a multinational study.
The study matched 36,927 tadalafil users, aged at least 40 years, with the same number of controls with LUTS who were not taking PDE5is. At baseline, the mean age was 62 years and participants did not have a history of glaucoma.
Unlike erectile dysfunction, men receiving tadalafil for LUTS take the drug daily.
During the five-year follow-up, 3.9% of men using tadalafil for LUTS and 3.2% of controls developed glaucoma, a statistically significant difference.
Men using tadalafil for LUTS were 22% more likely to develop glaucoma than controls. Tadalafil increased the risk of ocular hypertension (by 32%), primary open-angle glaucoma (by 33%) and starting glaucoma drugs and/or undergoing laser therapy (by 33%).
The risks of low-tension or primary angle-closure glaucoma in men on tadalafil for LUTS were not statistically significant.
“These findings suggest that chronic PDE5 inhibition may influence ocular physiology, warranting further mechanistic investigation,” the authors conclude.
“These findings do not contraindicate tadalafil use but highlight the importance of baseline ophthalmic assessment and regular follow-up, particularly in patients with pre-existing glaucoma, ocular hypertension, a family history of glaucoma, high myopia or those requiring long-term therapy.”
Br J Ophthalmol doi:10.1136/bjo-2026-329957
Eczema linked to shingles
Atopic dermatitis (AD) increases the risk of herpes zoster (HZ; shingles) independently of comorbidities, oral corticosteroids or immunosuppressants, according to an analysis of UK primary care records.
Adjusting for confounders, AD patients were 28% more likely to develop HZ than controls without eczema. HZ risk increased by 22% and 28% in people with mild and moderate AD respectively. However, HZ risk more than doubled in participants with severe AD (hazard ratio 2.33).
Adjusting for use of oral corticosteroids (24-27% increased HZ risk depending on the analysis) and other systemic immunosuppressants (27% increased risk) had little impact on the results. The risk of developing HZ increased by 17% after adjusting for topical corticosteroids.
The effect of AD on HZ risk was especially marked among younger people: increases of 51% and 42% in participants aged 30-40 and 40-50 years respectively.
Further studies should explore the underlying biological mechanisms, HZ recurrence, and the influence of vaccination status and other treatments.
Journal der Deutschen Dermatologischen Gesellschaft doi: 10.1111/ddg.70329

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