Diabetic Nephropathy Doctor — Valencia

How diabetes damages the kidneys

Diabetic nephropathy — also called diabetic kidney disease — is kidney damage caused by long-standing diabetes. It is one of the most common causes of chronic kidney disease worldwide and a leading reason people eventually need dialysis or a transplant. The good news is that it is largely preventable and treatable when caught early.

Persistently high blood glucose injures the tiny blood vessels of the glomeruli, the kidneys’ filtering units. Over years, the filters thicken, scar and become leaky, allowing protein (albumin) to escape into the urine. High blood pressure, which usually accompanies diabetes, accelerates this damage. The combination of high glucose and high pressure is what drives the kidneys’ gradual decline.

Dr. Juan Luis Villaro Gumpert, nephrologist at Hospital Vithas 9 de Octubre in Valencia, works closely with people who have diabetes to detect kidney involvement early and protect their long-term function, caring for Spanish and international patients in both English and Spanish.

The stages of diabetic nephropathy

Diabetic kidney disease progresses through recognisable stages:

• Microalbuminuria: small but abnormal amounts of albumin appear in the urine. This is the earliest detectable and most treatable stage, often present before any symptoms.
• Macroalbuminuria (overt proteinuria): larger amounts of protein are lost, blood pressure typically rises, and kidney function begins to fall.
• Progressive decline in eGFR: filtration falls steadily through the CKD stages, sometimes with swelling and fatigue.
• End-stage renal disease (ESRD): advanced kidney failure where dialysis or transplantation may become necessary.

Catching the condition at the microalbuminuria stage offers the best opportunity to slow or even reverse the process.

The link between HbA1c, blood pressure and kidney function

Two numbers do most of the damage — and most of the protection. HbA1c, a measure of average blood glucose over three months, reflects how well diabetes is controlled; keeping it at an individualised target reduces kidney injury. Blood pressure is equally critical: even modest reductions, generally to below 130/80 mmHg, meaningfully slow kidney decline. Controlling both, together with urinary protein, is the foundation of preserving kidney function in diabetes.

Screening recommendations

Because early diabetic nephropathy causes no symptoms, screening is essential. Everyone with type 2 diabetes should be tested from diagnosis, and those with type 1 diabetes from roughly five years afterwards, then at least annually. Screening uses a simple urine albumin-to-creatinine ratio plus a blood eGFR. Detecting microalbuminuria early allows treatment to begin while the kidneys can still recover.

Modern medications

Treatment has advanced significantly in recent years, and several medications now protect the kidneys directly:

• ACE inhibitors or ARBs lower blood pressure and reduce protein loss, and are first-line in diabetic nephropathy.
• SGLT2 inhibitors (such as dapagliflozin and empagliflozin) slow the decline of kidney function and cut protein loss, with benefits for the heart as well — a major advance in care.
• GLP-1 receptor agonists improve glucose control and weight, and increasingly show kidney and cardiovascular benefits.
• Non-steroidal mineralocorticoid receptor antagonists (such as finerenone) offer additional protection in selected patients.

These are layered onto good glucose and blood pressure control rather than replacing it.

Lifestyle management

Day-to-day habits make a real difference. A diet lower in salt helps control blood pressure, while individualised guidance on protein, potassium and phosphate matters as kidney function changes. Regular physical activity, achieving a healthy weight, stopping smoking and limiting alcohol all protect both the kidneys and the heart. Reviewing medications to avoid those that can harm the kidneys, such as certain anti-inflammatory painkillers, is also important.

With early screening, modern medication and consistent lifestyle measures, most people with diabetes can protect their kidneys for life. Dr. Villaro provides clear, English-language explanations and structured records that expat patients in Valencia can share with their diabetes team or doctor abroad, ensuring seamless, joined-up care.