Diabetic Nephropathy

Diabetic nephropathy, also known as diabetic kidney disease, is a complication of type 1 or type 2 diabetes that leads to impaired kidney function. It is a form of glomerulosclerosis (scarring of the glomerular tissue responsible for filtering the blood) caused by persistent hyperglycemia, resulting in proteinuria, that is, the presence of proteins in the urine.

It is estimated that one in three people with diabetes develops this type of kidney disease, making regular check-ups essential for early detection and slowing disease progression. These evaluations are particularly important because diabetic nephropathy usually does not cause symptoms until it has reached advanced stages.

Diabetic nephropathy is classified into five stages according to its severity:

• Stage I:
  • Normal blood pressure.
  • Absence of proteinuria.
  • Microalbuminuria greater than 20 mg/min (a value below 30 mg/g is considered normal).
  • Glomerular hyperfiltration: greater than 150 mL/min (a value between 90 and 150 mL/min is considered normal).
• Stage II:
  • Hypertension.
  • Absence of proteinuria.
  • Normal glomerular filtration rate or hyperfiltration.
  • Microalbuminuria greater than 20 mg/min.
• Stage III:
  • Proteinuria between 150 and 500 mg/24 hours.
  • Glomerular filtration rate between 130 and 160 mL/min.
  • Microalbuminuria between 20 and 200 mg/min.
• Stage IV:
  • Hypertension.
  • Proteinuria greater than 500 mg/24 hours.
  • Glomerular filtration rate between 10 and 130 mL/min.
  • Microalbuminuria above 200 mg/min.
• Stage V: The patient has end-stage chronic kidney disease, meaning the kidneys can no longer function adequately on their own. The glomerular filtration rate is below 10 mL/min.

The prognosis of diabetic kidney disease varies depending on how it is managed. It is generally favorable when both blood pressure and blood glucose levels are adequately controlled. However, if it is not detected early or the specialist’s recommendations are not followed, it may progress to kidney failure.

Symptoms

The symptoms of diabetic nephropathy develop progressively as the disease advances. The most common are:

• Nocturia: the need to urinate frequently during the night.
• Hypertension.
• Fatigue.
• Weakness.
• Loss of appetite.
• Edema (swelling) in the legs, ankles, or feet.
• Itchy skin.
• Difficulty concentrating.
• Sleep disturbances.
• Muscle cramps.

Causes

Diabetic nephropathy results from the hemodynamic changes (alterations in blood flow and blood pressure) and metabolic changes (abnormal chemical reactions that impair the conversion of food into energy) caused by diabetes. Specifically, the following alterations:

• Persistent hyperglycemia: damages the glomeruli responsible for filtering the blood.
• Hypertension: damages blood vessels.
• Inflammation: contributes to kidney deterioration.

Risk Factors

Diabetic nephropathy occurs only in patients with diabetes. The risk increases if they also present any of the following factors:

• Poorly controlled high blood glucose levels.
• Hypertension.
• Hypercholesterolemia.
• Smoking.
• Family history of kidney disease.

Complications

The main complications of diabetic nephropathy are:

• Edema in the extremities.
• Pulmonary edema.
• Cardiovascular disease.
• Stroke.
• Anemia: deficiency of red blood cells.
• End-stage kidney disease, meaning irreversible kidney damage.

Prevention

The best way to prevent diabetic nephropathy is to follow these recommendations:

• Maintain a healthy weight.
• Follow medical recommendations to control diabetes, particularly episodes of hyperglycemia.
• Control hypertension.
• Do not smoke.

Which specialist treats diabetic nephropathy?

Specialists in Nephrology diagnose and treat diabetic nephropathy. However, given its underlying cause, specialists in Endocrinology and Nutrition are also commonly involved in patient management.