This blood pressure drug may raise kidney risk in type 2 diabetes

Uncontrolled blood pressure can quietly damage the heart, brain, blood vessels and kidneys.

But medication decisions are rarely as simple as “take this pill and lower that number.”

Sometimes it matters what else that medication may be doing along the way.

That’s why new research on a widely used class of blood pressure drugs caught my attention — especially for people with type 2 diabetes.

Quick Answer: In a study of more than 31,000 adults with type 2 diabetes already taking two kidney-protective drug classes, those also taking dihydropyridine calcium channel blockers had a 33% higher risk of a major adverse kidney event than those taking other blood pressure drugs.

The study cannot prove the drugs caused the kidney problems, but researchers say the finding raises questions about whether they are always the best second-line choice in diabetic kidney disease.

A common blood pressure drug was linked to higher kidney risk

The study, published in Kidney Medicine, examined dihydropyridine calcium channel blockers, or DCCBs.

These drugs relax blood vessels and are widely used to lower blood pressure.

Researchers focused on a specific group: adults with type 2 diabetes who were already taking both a RAS inhibitor and an SGLT2 inhibitor.

RAS inhibitors include ACE inhibitors and ARBs. Along with lowering blood pressure, they can reduce pressure inside the kidney’s filtering structures.

SGLT2 inhibitors were developed to treat diabetes but are now also valued for their kidney- and heart-protective effects.

The researchers analyzed health records from 31,031 adults with type 2 diabetes.

All were taking both drug classes. Among them:

• 12,172 also took a DCCB
• 18,859 used other blood pressure medications instead

Over about 3.5 years, people taking DCCBs had a 33% higher adjusted risk of a major adverse kidney event.

Those events included either a drop of at least 40% in estimated glomerular filtration rate, or eGFR — a standard measure of kidney function — or progression to kidney failure.

The events were uncommon overall.

But they occurred significantly more often in the DCCB group.

Why type 2 diabetes makes this especially important

Diabetes and high blood pressure are already a rough combination for the kidneys.

High blood sugar can damage the tiny blood vessels involved in filtration, while high blood pressure adds even more strain.

That’s one reason RAS inhibitors and SGLT2 inhibitors have become so important in diabetic kidney care.

In fact, researchers thought their kidney-protective effects might help offset potential problems associated with DCCBs.

But the increased kidney risk persisted.

And that’s where the study becomes especially interesting.

How DCCBs may raise pressure inside the kidneys

DCCBs may affect kidney blood flow in a way that sounds almost contradictory.

According to the researchers, they may relax the blood vessels bringing blood into the kidney filters more strongly than the vessels carrying blood away.

That imbalance can allow pressure to remain high inside the glomeruli — the kidney’s delicate filtering structures.

In plain English: The drug may lower the blood pressure measured on your arm while still allowing too much pressure inside the kidneys.

That’s an important distinction.

And this isn’t the first time calcium channel blockers have raised questions about what may be happening beyond the cuff reading.

Earlier research we reported on found that L-type calcium channel blockers could trigger vascular changes involved in the kind of vessel remodeling these drugs are intended to prevent.

That earlier research involved a different mechanism and outcome.

But both studies point toward the same larger question:

Does a better blood pressure number always tell the whole story about what a drug is doing elsewhere in the vascular system?

Why this study matters beyond the blood pressure number

This was an observational study, so it cannot prove DCCBs directly caused the poorer kidney outcomes.

But the association remained after researchers adjusted for differences between the groups.

The study authors say their findings may help doctors weigh the potential risks and benefits of second-line blood pressure treatments in this population.

That makes this much more than an academic finding.

Supporting blood pressure from every angle

Medication and lifestyle don’t have to be opposing strategies. And for some people, blood pressure isn’t simply a matter of needing more treatment… it may be a matter of targeting the right mechanism. 

Blood pressure is influenced by movement, blood sugar, sleep, stress, weight and diet — giving us several areas where healthy habits can support the larger treatment picture.

We’ve reported on a simple mindfulness practice that lowered blood pressure by 15 points, and nitrate-rich foods such as beets and leafy greens can support nitric oxide and healthier blood vessel function.

That’s one reason the connection between beets, bacteria and blood pressure is worth understanding.

And because diabetes, kidney disease and cardiovascular health overlap so closely, this study also fits into the bigger story of cardiovascular-kidney-metabolic health, or CKM health.

The real takeaway

This study does not show that everyone taking a DCCB will develop kidney problems.

What it does show is that for people with type 2 diabetes already taking modern kidney-protective therapy, the choice of an additional blood pressure drug may matter more than has been previously realized.

That is a caution worth taking seriously. What matters, too, is what that medication may be doing elsewhere in the body.

Sources:

Widely prescribed blood pressure drugs linked to 33% higher kidney risk in type 2 diabetes — ScienceDaily / European Renal Association

Dihydropyridine Calcium Channel Blocker Therapy and Risk of CKD Progression in Type 2 Diabetes Treated With Renin Angiotensin System Inhibitors and SGLT2 Inhibitors: A Real-World Retrospective Cohort Study — Kidney Medicine

Managing High Blood Pressure Medications — American Heart Association

Chronic Kidney Disease and High Blood Pressure — CDC

Diabetes and Kidney Disease — National Kidney Foundation

FAQ: Blood pressure drugs, diabetes and kidney risk