What the tirzepatide CKD trial evidence tells us — and what it doesn't

Step 1: Understanding why CKD and tirzepatide trials intersect

CKD affects millions of adults in the UK, and many of them also live with obesity or type 2 diabetes, the two conditions tirzepatide is currently licensed to treat. That overlap is not coincidental. Excess weight and poorly controlled blood sugar are among the leading drivers of kidney damage over time, which is why researchers began asking whether a medicine effective at reducing both might also slow the progression of kidney disease itself.

There is a misconception worth addressing gently here: some people assume that because GLP-1 medicines are cleared partly by the kidneys, they must be dangerous in CKD. The picture is more nuanced than that. At lower kidney function, dose adjustments or additional monitoring may be needed, but the evidence to date does not show tirzepatide is uniformly contraindicated across all CKD stages. What matters is careful clinical assessment, not a blanket rule either way.

Tirzepatide works by activating two gut-hormone receptors, GIP and GLP-1, both of which play roles beyond appetite and blood sugar. Researchers have been exploring whether those pathways also affect kidney inflammation and the filtration processes that CKD disrupts. That mechanistic question is part of what drove the trial programme described below. You can read more about the broader tirzepatide trial programme and the conditions it has studied.

Step 2: What the SURPASS-CRRT trial studied and found

The SURPASS-CRRT trial was a phase 3 study examining tirzepatide specifically in adults with type 2 diabetes and moderate-to-severe CKD (estimated glomerular filtration rate, eGFR, below 60 mL/min/1.73m²). It was part of Eli Lilly's broader SURPASS programme, which built the evidence base behind tirzepatide's approvals, the SURPASS trials as a whole enrolled thousands of participants across multiple populations and comorbidities.

SURPASS-CRRT found that tirzepatide produced meaningful reductions in HbA1c (a measure of blood-sugar control) and body weight in participants with CKD, broadly consistent with results seen in the general SURPASS population. Importantly, the trial also looked at kidney-specific markers. Participants on tirzepatide showed reductions in urine albumin-to-creatinine ratio (UACR), a key indicator of how much protein is leaking through the kidneys, and a recognised marker of CKD progression. Slowing that leak is considered clinically significant.

Safety findings in SURPASS-CRRT were broadly in line with tirzepatide's known profile: gastrointestinal effects such as nausea and reduced appetite were the most common adverse events. No new safety signals specific to the CKD population emerged, though the trial was not powered to detect rare events. Researchers acknowledged that people with very low eGFR or on dialysis were not included, so evidence for the most advanced CKD stages remains limited. The cardiovascular outcome data for tirzepatide provides further context on how it performs in people with complex health conditions.

Step 3: Reading the evidence carefully, what's confirmed and what's still open

It is worth being precise about what the CKD trial data does and does not establish. The reduction in UACR is a meaningful signal, and the safety profile in moderate CKD appears manageable under clinical supervision. What the evidence does not yet provide is a long-term, dedicated kidney-outcomes trial for tirzepatide, comparable to the CREDENCE or DAPA-CKD trials that established kidney-protective effects for SGLT-2 inhibitors. That kind of evidence takes years to accumulate.

Regulators in the UK (principally the MHRA) license medicines on the totality of submitted evidence. Tirzepatide's current UK licence covers weight management and type 2 diabetes. Any prescribing in a person with CKD sits within those indications and requires the prescriber to weigh kidney function, current medicines, and overall health. People already on medicines commonly used in CKD (such as ACE inhibitors, ARBs, or SGLT-2 inhibitors) need their whole medication list reviewed before tirzepatide is added. That is a conversation for a prescriber, not a checklist. For a full overview of what tirzepatide is and how it works, the NHS medicines page is a reliable starting point.

The Mounjaro trial evidence page covers the broader weight-loss data, including SURMOUNT-1, which reported an average body-weight reduction of around 20–21% at the 15mg dose over 72 weeks in adults with obesity. That trial did not focus specifically on CKD, but participants with various cardiometabolic risk factors were included.

Step 4: What this means in practice if you have CKD and are considering tirzepatide

If you have been diagnosed with CKD and are also dealing with obesity or type 2 diabetes, it is reasonable to ask whether tirzepatide could be appropriate for you. The trial evidence is encouraging enough that the conversation is worth having with a prescriber, but the answer depends on your specific kidney function, how stable your CKD is, what other medicines you take, and whether weight management is a current clinical priority.

A prescriber reviewing your case will want to know your most recent eGFR and UACR results, your current medication list, and any history of acute kidney injury. Tirzepatide titration (starting at 2.5mg and increasing gradually) may be slower or more cautious in someone with reduced kidney function, to give the body time to adjust and to monitor any changes in kidney markers.

For context on what treatment might cost privately, the Mounjaro pricing page sets out what is typically included in a private prescription service. If you would like to explore whether tirzepatide could be right for your situation, a good next step is a clinical consultation with a prescriber who can look at your full health picture. You can check your eligibility with our prescribers at any point, it is a free consultation, reviewed the same day by a real clinician.