Semaglutide in diabetic kidney disease: primary MRI outcomes not met in 52-week trial

The study

This was a randomised, placebo-controlled trial in people with type 2 diabetes and chronic kidney disease. Participants received subcutaneous semaglutide 1 mg once weekly or placebo for 52 weeks. In total, 106 people took part (25 women and 81 men).

The aim was to understand how semaglutide may protect the kidney. The authors used multiparametric kidney MRI in the trial. A subset also had kidney biopsy for histology (n = 33). Paired before-and-after samples were studied with single-nucleus transcriptomics (n = 22) and spatial transcriptomics (n = 13). The trial is registered as NCT04865770.

What they found

The three coprimary MRI outcomes were not significantly altered by semaglutide versus placebo. These were oxygenation (R2*), global perfusion and tissue inflammation (T1 mapping).

Secondary outcomes gave a more positive picture:

• Semaglutide was associated with a significantly reduced renal artery resistive index compared with placebo.
• The apparent diffusion coefficient was stabilised. The authors interpret this as prevention of fibrosis progression.
• Transcriptomic analyses showed pronounced effects on glomerular endothelial cells.
• Spatial analyses indicated fewer immune cells close to these endothelial cells.

The authors conclude that kidney protection by semaglutide may include reduced vascular resistance, prevention of fibrosis and improved molecular programmes that support endothelial cell health.

How much weight to give it

Treat this as early, mechanistic evidence. The main points to keep in mind:

• The trial did not meet its coprimary outcomes. The positive findings come from secondary outcomes, which are better seen as hypothesis-generating.
• The abstract does not report whether the analysis was adjusted for multiple testing.
• The outcomes are imaging and molecular markers. They are surrogates, not hard outcomes such as kidney failure or death.
• The study is small. The biopsy and transcriptomic subsets are smaller still (n = 33, 22 and 13).
• Follow-up was 52 weeks.
• The abstract does not report effect sizes, confidence intervals, kidney function results, safety data or funding. Only 25 of the 106 participants were women, so findings in women are less certain.

The abstract opens by stating that semaglutide preserves kidney function in this population. This trial was not designed to test that claim. It looks at possible mechanisms.

For your clinic

This study does not change who should receive semaglutide. It offers a possible biological explanation for kidney effects seen elsewhere, through vascular and anti-fibrotic pathways. It does not prove those pathways are the cause of any benefit.

For decisions about kidney protection in type 2 diabetes, continue to rely on outcome trials and current guidelines. Read the full paper before drawing conclusions. In particular, check the effect sizes, the handling of multiple secondary outcomes, the baseline kidney function of participants and the safety data.