FLOW published: semaglutide cuts kidney disease progression by 24 percent

The New England Journal of Medicine published the FLOW trial, which tested whether once-weekly injectable semaglutide could slow kidney disease in people with type 2 diabetes. Among 3,533 adults, semaglutide reduced the risk of major kidney disease events by 24 percent compared with placebo, and an independent review recommended stopping the trial early because the benefit was clear ^[1].

What the trial tested

FLOW enrolled adults with type 2 diabetes and chronic kidney disease, defined by kidney filtering rate and protein in the urine. Participants needed an estimated glomerular filtration rate (eGFR) of 50 to 75 mL/min/1.73 m² with a urinary albumin-to-creatinine ratio above 300 and below 5000, or an eGFR of 25 to under 50 with a ratio above 100 and below 5000 ^[1].

Participants were randomly assigned to subcutaneous semaglutide 1.0 mg weekly (1,767 people) or placebo (1,766 people) on top of usual care ^[1]. That 1 mg weekly dose is the strength sold as Ozempic for type 2 diabetes; Wegovy is the same molecule at higher doses for weight management ^[4].

The primary outcome was a composite of kidney failure (dialysis, transplant, or an eGFR below 15), at least a 50 percent drop in eGFR from baseline, or death from kidney-related or cardiovascular causes ^[1]. The trial was funded by Novo Nordisk and registered as NCT03819153 ^[1][2].

The numbers

Median follow-up was 3.4 years, shortened after a prespecified interim analysis prompted the recommendation to stop early ^[1]. There were 331 first primary-outcome events in the semaglutide group versus 410 with placebo — a hazard ratio of 0.76 (95% confidence interval, 0.66 to 0.88; P = 0.0003) ^[1].

The kidney-only parts of that composite moved in the same direction (hazard ratio 0.79; 95% CI, 0.66 to 0.94), as did death from cardiovascular causes (hazard ratio 0.71; 95% CI, 0.56 to 0.89) ^[1].

All prespecified confirmatory secondary outcomes favored semaglutide. The average yearly decline in eGFR was slower by 1.16 mL/min/1.73 m² (P<0.001). Major cardiovascular events were 18 percent lower (hazard ratio 0.82; 95% CI, 0.68 to 0.98; P = 0.029), and death from any cause was 20 percent lower (hazard ratio 0.80; 95% CI, 0.67 to 0.95; P = 0.01) ^[1].

On safety, serious adverse events were reported in fewer people taking semaglutide than placebo: 49.6 percent versus 53.8 percent ^[1]. The published abstract does not break out rates of specific side effects such as nausea, so those details are not available here ^[1].

Why it matters for patients

Chronic kidney disease is common in type 2 diabetes, and people with both face high risks of kidney failure, heart events and death ^[1]. Until FLOW, it was unknown whether semaglutide changed those outcomes ^[1]. The trial results give doctors randomized evidence that a GLP-1 drug many patients already take for blood sugar also slowed kidney decline in this specific, higher-risk group.

A few limits are worth knowing. FLOW studied the injectable 1 mg weekly dose, not the higher weight-management doses and not the pill ^[1]. The results also apply to people who met the trial's eGFR and albumin thresholds — that is, people with measurable kidney damage — not to everyone with diabetes ^[1].

The findings also do not automatically transfer to oral semaglutide. In the later SOUL trial of oral semaglutide up to 14 mg daily in 9,650 people at high cardiovascular risk, the major kidney disease outcome did not differ from placebo, which stopped the trial's hierarchical testing at that point ^[3]. Commentators suggested possible reasons including higher baseline eGFR in SOUL, lower bioavailability of the oral form, or chance ^[3].

What happens next

On January 28, 2025, the FDA approved Ozempic to reduce the risk of sustained eGFR decline, end-stage kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease ^[4]. Ozempic injection carries a boxed warning for thyroid C-cell tumors, along with warnings that include pancreatitis, diabetic retinopathy complications, low blood sugar, acute kidney injury from volume depletion, severe gastrointestinal reactions and gallbladder disease ^[4].

Ozempic tablets, approved in the US under that name on January 30, 2026, are indicated for type 2 diabetes and for reducing major cardiovascular events — not for the kidney outcome ^[4].