Choosing the right diabetes medication involves more than controlling blood sugar. Protecting the kidneys is equally important, yet not every patient appears to benefit from the same treatment.

A study published in The BMJ on 16 September 2026 suggests that a routine liquid waste test could help doctors make more individualised treatment decisions by identifying patients who may benefit most from certain kidney-protective medicines.

What A Liquid Waste Test Reveals

Researchers at Mass General Brigham investigated whether the presence of albumin, a protein that can indicate kidney damage when detected in liquid waste, influences the effectiveness of different diabetes medications.

The study analysed medical records from 75,455 adults with type 2 diabetes across the United States. Of these, 13,872 had albuminuria, while 61,583 showed no evidence of the condition.

All participants had moderate cardiovascular risk and were taking metformin before starting an additional diabetes medication. Their median age was 60, and researchers followed their health outcomes for a median of 32 months, estimating risks over five years.

The investigation compared newer treatments, including GLP-1 receptor agonists and SGLT2 inhibitors, with two other medication classes: DPP-4 inhibitors and sulfonylureas.

Different Patients, Different Results

The findings revealed an important difference between patients with and without albuminuria. Among those with albuminuria, the estimated five-year risk of serious kidney deterioration was 3.2% for patients receiving GLP-1 receptor agonists or SGLT2 inhibitors, compared with 5.4% for those taking DPP-4 inhibitors.

However, the results were different for participants without albuminuria. Their estimated risks were 2.4% and 2.1%, respectively, providing little evidence of additional kidney protection from the newer treatments within this study.

The researchers also observed that sulfonylureas were associated with a greater risk of kidney deterioration than DPP-4 inhibitors among patients without albuminuria.

Moving Beyond Standard Treatment

The results highlight the potential value of tailoring diabetes care to individual kidney health rather than relying on the same medication strategy for every patient.

Corresponding author Alexander Turchin explained that liquid waste testing could help clinicians identify patients who may gain additional kidney protection from newer medications, while also recognising situations in which alternative treatments warrant closer consideration.

A liquid waste albumin test is relatively straightforward and could provide useful information alongside blood glucose measurements, kidney function tests and cardiovascular risk assessments.

Rather than replacing existing diagnostic procedures, the findings suggest that albuminuria could become another important factor in discussions about medication choices.

Why More Research Is Needed

Despite the findings, the study has important limitations. Researchers analysed existing medical records using a method designed to emulate a clinical trial, rather than randomly assigning participants to treatments.

The analysis also grouped GLP-1 receptor agonists and SGLT2 inhibitors together, although these medications have different biological mechanisms.

Importantly, the absence of a statistically significant benefit among patients without albuminuria does not prove that the treatments offer them no kidney protection. Other clinical research has identified benefits from SGLT2 inhibitors even among people with low urinary albumin levels.

Towards More Personalised Care

The findings reinforce the importance of assessing individual risk when selecting diabetes medications. They also highlight the need for further research into preventing kidney disease before measurable damage develops.

For clinicians, a simple liquid waste test could provide another piece of information when balancing potential benefits and risks. For patients, the research offers a reminder that effective diabetes management depends on understanding individual health needs rather than assuming that one treatment will produce identical results for everyone.