Among more than 31,000 adults with type 2 diabetes, those taking dihydropyridine calcium-channel blockers had a 33% higher risk of a major kidney event than those on other blood pressure drugs. The finding, presented at the European Renal Association Congress 2026, comes from patients who were already receiving today's standard kidney-protective medications.
Calcium-channel blockers are one of the most widely prescribed drug families in the United States. The best known is amlodipine, sold under brand names such as Norvasc, and it sits near the top of the country's most-dispensed medications every year, according to prescription-claims data compiled by ClinCalc.
What the study measured
Researchers followed 31,031 adults with type 2 diabetes from 2016 through 2021, using data from Israel's Clalit Health Services. All were already taking two pillars of modern kidney care: RAS inhibitors, a class that lowers pressure inside the kidney's filtering units, and SGLT2 inhibitors, a newer group of drugs shown to slow diabetic kidney damage.
About 12,000 of the patients were also on a dihydropyridine calcium-channel blocker, often added as a second drug when blood pressure remains high. Over roughly 3.5 years, the calcium-channel blocker group had a 33% higher risk of a "major adverse kidney event," defined as either a 40% or greater drop in kidney filtration or progression to end-stage kidney disease requiring dialysis or a transplant, Healio reported from the congress.
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A possible reason: pressure inside the kidney
Researchers proposed a plausible mechanism. Each kidney contains millions of tiny filters called glomeruli, fed by an incoming vessel and drained by an outgoing one. Dihydropyridine calcium-channel blockers appear to relax the incoming vessel more strongly than the outgoing one, which can push pressure inside the filter up rather than down.
"DCCBs selectively dilate the afferent arteriole of the glomerulus, which increases renal blood flow and intraglomerular pressure," lead author Timna Agur, a senior nephrologist at Rabin Medical Center in Israel, told Healio. She added that "over time, this may promote hyperfiltration, proteinuria and potentially structural kidney damage," a process that is already a driver of diabetic kidney disease.
The team had expected SGLT2 inhibitors to blunt any downside. "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," Agur said in a statement issued by the European Renal Association.
What patients should not do
The results come with an important limit. The study is observational, meaning it can show a link but cannot prove that the drugs themselves caused the worse outcomes. Unmeasured differences between patients who did and did not receive the drug class could still explain part of the effect.
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Agur said further work is needed. "Further prospective studies and randomised controlled trials are needed to confirm these observations and better define the safest blood pressure treatment strategies for patients with DKD," she said.
For anyone currently taking a calcium-channel blocker, one message from clinicians is consistent: do not stop or change a prescription based on a single study. Uncontrolled high blood pressure carries its own well-documented risks for the heart, brain and kidneys. Concerns about a specific pill are a reason to book a conversation with the prescribing doctor, not to skip the next dose.
Type 2 diabetes now affects more than 38 million adults in the United States, according to the Centers for Disease Control and Prevention, and diabetic kidney disease is one of its most common serious complications. That overlap is what makes findings like these worth paying attention to, even while the science is still catching up.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.