A large real-world study suggests that one of the most commonly prescribed blood pressure medications may not protect diabetic kidneys as well as previously thought, even when patients are already taking today's most powerful kidney-saving drugs. Researchers analyzing data from over 31,000 adults with type 2 diabetes found that those taking dihydropyridine calcium-channel blockers (DCCBs) faced a significantly higher risk of kidney disease progression compared to those using other blood pressure treatments.

Why Does Blood Pressure Control Matter So Much for Diabetic Kidneys?

High blood sugar from diabetes damages the tiny blood vessels in the kidneys that filter waste from the blood. Over time, this damage can lead to kidney failure, requiring dialysis or transplantation. High blood pressure makes this problem worse by placing additional strain on kidneys that are already struggling. That's why managing blood pressure has long been considered one of the most important parts of treating diabetic kidney disease (DKD).

In recent years, treatment has improved dramatically with two major medication classes. Renin-angiotensin system (RAS) inhibitors reduce pressure inside the kidney's filtering units, while sodium-glucose cotransporter-2 (SGLT2) inhibitors have emerged as powerful kidney-protective drugs that can slow disease progression. Despite these advances, many patients still need additional medications to control blood pressure, and DCCBs have become one of the most frequently prescribed options.

What Did the Study Find About DCCB Use?

Researchers examined data from 31,031 adults with type 2 diabetes between 2016 and 2021. Every participant was already receiving both RAS inhibitors and SGLT2 inhibitors. Of those patients, 12,172 (about 39%) were also taking DCCBs, while 18,859 (about 61%) were using other blood pressure medications. Participants were followed for a median of about 3.5 years.

After accounting for differences in clinical and demographic factors, the researchers found that DCCB use was associated with a 33% greater risk of a major adverse kidney event. These events included either a decline of at least 40% in estimated glomerular filtration rate (eGFR), a key measure of kidney function, or progression to end-stage kidney disease requiring dialysis or a kidney transplant.

"DCCBs are widely used as second-line blood pressure treatments in patients with DKD. Our findings raise important questions about whether these medications are always the best option for patients already receiving modern kidney-protective therapies," said Dr. Timna Agur, lead author of the study.

Dr. Timna Agur, Lead Author, 63rd ERA Congress Study

How Might DCCBs Affect Kidney Function Differently?

The researchers believe the results may be related to how DCCBs influence blood flow inside the kidneys. In people with diabetic kidney disease, the kidneys are often already under increased pressure because of a condition called hyperfiltration, in which the filtering units are working harder than normal.

DCCBs work by relaxing blood vessels to lower blood pressure. However, the researchers suggest that these medications may primarily relax the blood vessels that carry blood into the kidney's filtering units while having less effect on the vessels that carry blood away. This imbalance could increase pressure within the filters themselves and potentially contribute to ongoing kidney damage.

Surprisingly, the increased risk of kidney disease progression appeared to persist even in patients who were also taking SGLT2 inhibitors, the powerful kidney-protective drugs that have transformed diabetic kidney disease treatment.

What Should Patients and Doctors Know?

The researchers emphasized that the study was observational and does not prove that DCCBs directly cause worsening kidney disease. However, they say the findings are important because these medications are widely prescribed for patients with diabetic kidney disease, affecting millions of people worldwide.

• Study Scope: The analysis included 31,031 adults with type 2 diabetes, making it a large real-world examination of medication safety in this population.
• Risk Increase: DCCB use was associated with a 33% greater risk of major adverse kidney events, a clinically meaningful difference that could affect treatment decisions.
• Medication Classes: The findings raise questions about whether alternative blood pressure medications might be safer options for patients already receiving RAS inhibitors and SGLT2 inhibitors.

"We initially thought the kidney-protective effects of SGLT2 inhibitors might counterbalance the potential harms associated with DCCBs. However, the increased risk of kidney disease progression appeared to persist even in this group," explained Dr. Agur.

Dr. Timna Agur, Lead Author, 63rd ERA Congress Study

The researchers called for further prospective studies and randomized controlled trials to confirm these observations and better define the safest blood pressure treatment strategies for patients with diabetic kidney disease. Given how commonly these medications are prescribed, any increase in kidney risk could have important implications for large numbers of patients.

For now, the findings suggest that patients with diabetic kidney disease should discuss their blood pressure medications with their healthcare providers, particularly if they are already taking modern kidney-protective therapies. The choice of blood pressure medication may matter more than previously thought for protecting kidney function in this vulnerable population.