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Broad Efficacy Across Subgroups
SGLT2 inhibitors (SGLT2i) demonstrated a consistent reduction in kidney disease progression, acute kidney injury (AKI), and all-cause hospitalization regardless of whether a patient has type 2 diabetes or the level of baseline albuminuria.
Significant Relative Risk Reductions
The therapy reduced the risk of kidney disease progression by 35% in participants with diabetes and by 26% in those without diabetes. Similarly, risks for AKI and all-cause mortality were significantly lowered across both cohorts.
Absolute Benefits in Low-Albuminuria Populations
While the greatest absolute renal benefits were observed in patients with high albuminuria (UACR ≥200 mg/g), participants with lower albuminuria levels still experienced substantial absolute reductions in hospitalizations and other clinical events.
Background: The Evolution of SGLT2i in Renal Care
Sodium-glucose cotransporter 2 (SGLT2) inhibitors have transitioned from their initial role as glucose-lowering agents to fundamental pillars of organ-protective therapy. Clinical trials such as DAPA-CKD and EMPA-KIDNEY have previously established their efficacy in slowing the decline of kidney function. However, clinical guidelines have historically varied in their strength of recommendation based on a patient’s diabetes status and the degree of albuminuria, often defined by the urine albumin-to-creatinine ratio (UACR). There has been lingering uncertainty regarding the magnitude of benefit for patients with non-diabetic chronic kidney disease (CKD) or those with low levels of proteinuria, leading to potential under-utilization in these populations.
Study Design: The SMART-C Meta-Analysis
The SGLT2 Inhibitor Meta-Analysis Cardio-Renal Trialists’ Consortium (SMART-C) conducted a comprehensive meta-analysis to address these uncertainties. The study included data from 8 randomized clinical trials focusing on SGLT2 inhibitors with label indications for kidney disease. A total of 58,816 participants were analyzed, with a mean age of 64 years. Of these, 48,946 had diabetes and 9,870 did not. The primary objective was to assess both relative and absolute effects on efficacy and safety outcomes, stratified by diabetes status and UACR (threshold of 200 mg/g).
The methodology employed an inverse variance-weighted meta-analysis. Absolute effects were estimated by applying the calculated relative risks to the event rates observed in the placebo groups, providing a clear picture of the clinical impact in real-world scenarios.
Key Findings: Efficacy Across the Spectrum
Kidney Disease Progression
The meta-analysis confirmed that SGLT2i significantly lower the rate of kidney disease progression. In participants with diabetes, the rate was 33 per 1000 patient-years in the SGLT2i group versus 48 in the placebo group (Hazard Ratio [HR], 0.65; 95% CI, 0.60-0.70). In those without diabetes, the rates were 32 vs 46 per 1000 patient-years (HR, 0.74; 95% CI, 0.63-0.85). The similarity in hazard ratios suggests that the biological mechanism of nephroprotection is largely independent of glucose metabolism.
Acute Kidney Injury (AKI) and Hospitalization
A notable finding was the consistent reduction in AKI, a common concern in patients with advanced CKD. The HR for AKI was 0.77 for those with diabetes and 0.72 for those without. Furthermore, the risk of any hospitalization was reduced by approximately 10-11% across both groups. This highlights the systemic benefits of SGLT2i, which extend beyond the kidneys to broader cardiovascular and metabolic stability.
Mortality Outcomes
The analysis showed a lower rate of any death in participants with diabetes (HR, 0.86; 95% CI, 0.80-0.91). While the mortality benefit in the non-diabetic group was slightly less pronounced (HR, 0.91; 95% CI, 0.78-1.05), the overall trend remained favorable, supporting the use of these agents in a wide range of CKD patients.
The Role of Albuminuria: Absolute vs. Relative Benefits
One of the most critical aspects of this study was the stratification by UACR. The relative risk reductions for kidney progression were remarkably consistent across UACR levels. However, the absolute benefits differed. Because patients with a UACR ≥200 mg/g are at a higher baseline risk for kidney failure, the absolute number of events prevented was higher in this group.
Conversely, in patients with a UACR <200 mg/g, while the absolute renal benefit was numerically smaller, the absolute benefit in preventing hospitalizations remained highly significant. This suggests that even in the absence of heavy proteinuria, SGLT2i provide substantial clinical value by reducing the overall healthcare burden and improving patient stability.
Expert Commentary: Implications for Clinical Guidelines
The findings from the SMART-C consortium reinforce a growing consensus: SGLT2 inhibitors should be considered a foundational therapy for most patients with chronic kidney disease, regardless of their glycemic status. The data suggests that the current focus on high-albuminuria populations in some guidelines may be too narrow.
From a mechanistic standpoint, the benefits are likely driven by a reduction in intraglomerular pressure, improved oxygenation of the renal medulla, and reduced inflammatory markers. These effects occur independently of the insulin-glucose axis, which explains why non-diabetic patients benefit nearly as much as those with type 2 diabetes. Clinicians should also note that the net absolute benefits persisted in populations without heart failure and in those with an eGFR below 60 mL/min/1.73 m2, further broadening the eligible patient base.
Conclusion: A Universal Tool for Renal Protection
This meta-analysis provides the most robust evidence to date that the benefits of SGLT2 inhibitors are universal across the studied CKD spectrum. By reducing the risks of kidney failure, AKI, and hospitalization, these agents offer a powerful tool to alter the trajectory of chronic kidney disease. Future clinical practice should prioritize the initiation of SGLT2i in CKD patients based on their overall risk profile rather than strict adherence to diabetes or albuminuria thresholds alone.
References
Staplin N, Roddick AJ, Neuen BL, et al. Effects of Sodium Glucose Cotransporter 2 Inhibitors by Diabetes Status and Level of Albuminuria: A Meta-Analysis. JAMA. 2026;335(3):220-232. doi:10.1001/jama.2025.20835.