SGLT2 Inhibitors at Low GFR: Are We Drawing the Line in the Wrong Place?

The SGLT2 inhibitors have had a profound effect on chronic disease management, in particular, in those living with chronic kidney disease, heart failure, or seeking to reduce cardiovascular risk in type 2 diabetes.

There has been a quiet but profound shift in how we understand and use them. What began as a class of glucose-lowering agents has become central to the management of chronic kidney disease and heart failure. Most clinicians now recognize their role in slowing kidney decline and reducing cardiovascular events.

And yet, when kidney function falls into the low 20s – or below – many of us still hesitate.

That hesitation is not unreasonable. It reflects how these drugs were originally studied and how their use was first framed. But it is increasingly at odds with what we now understand about how they work and where their benefits lie.

How the Threshold Entered Practice

The commonly cited eGFR “floor” for SGLT2 inhibitors comes from the major clinical trials – CREDENCE, DAPA-CKD, and EMPA-KIDNEY.

Each of these studies required a minimum eGFR for enrollment, generally in the range of 20 to 30 mL/min/1.73 m². That decision has often been interpreted as implying that the drugs are ineffective or unsafe below those levels.

In reality, those thresholds were pragmatic. At the time these trials were designed, SGLT2 inhibitors were still largely viewed through a glycemic lens, and there was understandable caution about introducing them in advanced CKD. Trial populations also need to be bounded to allow for interpretable results.

Over time, however, those entry criteria have taken on a life of their own. What began as a study design choice has come to feel like a biological boundary.

What the Trials Actually Tell Us

One detail that tends to receive less attention is what happened after patients entered these trials.

Kidney function did not remain static. Many participants experienced progressive decline in eGFR, often falling well below the initial enrollment threshold. In general, however, they were not required to discontinue therapy as this occurred. Regulatory summaries of these trials now make this explicit, noting that patients in studies such as DAPA-CKD and related programs continued therapy even as eGFR declined below the entry criteria.

Importantly, there was no signal that benefit disappeared once a patient crossed an arbitrary eGFR value. Nor was there a late-emerging safety concern specific to lower levels of kidney function.

This creates a situation that is difficult to reconcile clinically. A patient who began treatment at an eGFR of 28 and has since declined to 17 is typically continued on therapy without much debate. A patient who first presents at an eGFR of 17, however, may be considered a less appropriate candidate to start.

The physiology in these two situations is the same. The difference lies in how the evidence was generated, not in how the drug behaves.

Moving Beyond the Glycemic Frame

Part of the persistence of this threshold comes from the way these drugs were originally conceptualized.

It remains true that the glucose-lowering effect of SGLT2 inhibitors diminishes as eGFR falls. With less filtered glucose, there is less glycosuria, and HbA1c reductions become modest.

But the outcomes that have driven their widespread adoption in CKD are not primarily related to glycemic control.

The more relevant mechanism is hemodynamic. By inhibiting sodium reabsorption in the proximal tubule, these agents increase sodium delivery to the macula densa, restore tubuloglomerular feedback, and reduce intraglomerular pressure. This results in a functional “unloading” of the glomerulus.

That mechanism does not appear to switch off at a specific eGFR. It is active in moderate CKD and, based on both physiology and trial experience, likely remains operative in more advanced stages as well.

Once one accepts that the benefit is largely independent of glucose lowering, the rationale for a strict lower threshold becomes less clear.

Interpreting the Early Rise in Creatinine

The initial rise in serum creatinine that accompanies SGLT2 inhibitor initiation continues to generate concern, particularly in patients with more advanced CKD.

At lower baseline eGFR, even a modest increase can feel consequential. It is often interpreted, understandably, as a sign that the kidney is being harmed.

However, in most cases, this early change reflects a reduction in intraglomerular pressure rather than structural injury. The same principle underlies the rise in creatinine seen with initiation of ACE inhibitors or ARBs – a phenomenon that is now widely accepted as part of their renoprotective effect.

Seen in that light, the early “dip” in eGFR is less a complication than an expected physiological response. It requires clinical judgment, particularly in patients at risk of volume depletion or other competing insults, but it should not automatically be viewed as a reason to avoid or discontinue therapy.

Where the Benefit May Be Greatest

Another important consideration is how treatment effect translates into clinical benefit across different levels of kidney function.

Meta-analyses, including large collaborative work led by David Neuen, suggest that relative risk reductions for kidney outcomes are broadly consistent across eGFR strata. However, because baseline risk is substantially higher in patients with more advanced CKD, the absolute benefit may be greater in this group.

In practical terms, a modest slowing of decline at an eGFR of 20 may translate into a meaningful delay in the need for dialysis. That is often of greater consequence to patients than a similar relative effect earlier in the disease course.

This raises an important question: are we withholding therapy from the very patients who stand to gain the most?

The Evolving Position of Guidelines

Guidelines have begun to reflect this shift in understanding.

KDIGO recommends SGLT2 inhibitors in patients with diabetes and CKD down to an eGFR of 20 mL/min/1.73 m² and explicitly notes that the reversible fall in eGFR after initiation is generally not a reason to stop therapy.

Diabetes Canada (2025 update) supports their use in patients with eGFR 20–45, even in the absence of significant albuminuria in many cases.

American Diabetes Association similarly recommends SGLT2 inhibitors for patients with CKD down to an eGFR of 20 for kidney and cardiovascular protection.

At the same time, regulatory labeling remains somewhat heterogeneous. For example, Jardiance (empagliflozin) does not specify a strict lower eGFR threshold for heart failure indications, whereas Farxiga (dapagliflozin) continues to advise against initiation below eGFR 25 while permitting continuation if kidney function later declines.

Taken together, this reflects a field in transition. The conceptual model has shifted, but the practical boundaries have not fully aligned.

A Practical Way to Approach the Patient at Low GFR

When considering whether to initiate an SGLT2 inhibitor in a patient with advanced CKD, it may be helpful to reframe the question.

Rather than focusing primarily on whether the patient meets the entry criteria of a particular trial, one might ask:

• Is the underlying mechanism of benefit still relevant at this level of kidney function?

• Is there evidence, direct or indirect, that benefit persists as eGFR declines?

• Would I be comfortable continuing this therapy if the patient had already been on it?

If the answer to the last question is yes, it is worth examining why initiation feels different.

That difference may be more reflective of how the evidence was generated than of any meaningful change in biology.

Conclusion

SGLT2 inhibitors are no longer best understood as glucose-lowering drugs. Their primary role in CKD is to modify intraglomerular hemodynamics and reduce the downstream consequences of hyperfiltration and injury.

The eGFR thresholds that continue to shape prescribing patterns originated as pragmatic decisions in clinical trial design. Over time, they have been interpreted as markers of biological effectiveness.

As evidence accumulates and guidelines evolve, that interpretation is becoming harder to sustain.

For clinicians, the challenge is not simply to follow thresholds, but to understand where they came from – and when it may be reasonable to look beyond them.

References

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