Summary: In a 32-week post hoc MRI substudy of 80 patients with type 2 diabetes at high cardiovascular risk, semaglutide and empagliflozin each significantly reduced cortical apparent diffusion coefficient (ADC) versus placebo (semaglutide -0.20×10-3 mm2/s, p<0.001; empagliflozin -0.15×10-3 mm2/s, p=0.01), while combination therapy did not. Total kidney volume fell by -3% with each monotherapy and -5% with combination therapy. These are exploratory imaging findings, not clinical kidney outcomes.
PICO Summary
| Element | Detail |
|---|---|
| Population | 80 patients with type 2 diabetes and high cardiovascular risk; post hoc MRI substudy of a randomised controlled trial conducted in Denmark. |
| Intervention | Semaglutide alone (n=20) or semaglutide plus empagliflozin combination therapy (n=20) over 32 weeks; empagliflozin monotherapy (n=20) assessed in a parallel arm. |
| Comparison | Tablet placebo (n=20) over the same 32-week period. |
| Outcome | Cortical ADC vs placebo: semaglutide -0.20×10-3 mm2/s (95% CI -0.30, -0.10; p<0.001); empagliflozin -0.15×10-3 mm2/s (95% CI -0.26, -0.04; p=0.01); combination -0.05×10-3 mm2/s (95% CI -0.15, 0.05; p=0.29, not significant). Total kidney volume vs placebo: semaglutide -3% (95% CI -5%, -0.3%; p=0.04), empagliflozin -3% (95% CI -5%, -0.4%; p=0.02), combination -5% (95% CI -8%, -2%; p<0.001). Cortical ADC changes were not associated with GFR, albuminuria, total kidney volume or inflammation; kidney volume changes were associated with GFR, albuminuria and HbA1c. No clinical renal outcomes, ARR or NNT were reported. |
Renal DWI-MRI with semaglutide & empagliflozin
RCT substudy · type 2 diabetes · 32 weeks
Semaglutide and empagliflozin each lowered cortical ADC vs placebo; combination did not. Exploratory imaging surrogates, not clinical kidney outcomes.
Expert Commentary
This substudy is best read as mechanistic and hypothesis-generating rather than as evidence of renal protection. Because it is a post hoc analysis of a small 80-patient trial with only 20 participants per arm, it was not powered to detect clinical kidney outcomes, and the endpoints reported are imaging surrogates. A reduction in cortical ADC was initially proposed to reflect kidney fibrosis, yet the authors are careful to note that the changes seen here were not associated with GFR, albuminuria or inflammatory markers, so the signal may reflect altered renal water diffusion or haemodynamics rather than structural fibrosis. The parallel reduction in total kidney volume, which did track with GFR, albuminuria and HbA1c, is consistent with the favoured explanation of reduced glomerular hyperfiltration. One weighed limitation deserves emphasis: the combination arm showed no significant cortical ADC change despite producing the largest kidney volume reduction, which argues against a simple dose-additive interpretation and cautions against overreading any single imaging measure. Can I use this with my patients? Not yet, at least not as a reason to change prescribing; the established renal benefit of these agents rests on outcome trials, not on this MRI signal. What is genuinely useful here is the proof of concept that diffusion-weighted MRI can be deployed to probe drug mechanisms in diabetic kidney disease. Larger studies that anchor these imaging changes to histology and to hard renal endpoints are needed before ADC can inform clinical decisions.
References
Vernstrom L, Gullaksen S, Sorensen SS, Ringgaard S, Laustsen C, Birn H, et al. Effects of semaglutide, empagliflozin and their combination on renal diffusion-weighted MRI and total kidney volume in patients with type 2 diabetes: a post hoc analysis from a 32 week randomised trial. Diabetologia. 2024;67(10):2175-2187. doi:10.1007/s00125-024-06228-y