Diabetic Nephropathy: Diabetes and Kidney Health

Diabetes affects glucose metabolism, which creates a hostile environment for most organ systems of the body, including the heart, blood vessels, skin, liver, and kidneys. The kidneys are especially at risk because of their role in blood filtration.

Here’s how diabetic nephropathy happens, the symptoms that people with diabetes experience as a result, and how diabetes-induced kidney damage is treated.

Diabetic nephropathy is a long-term kidney disease that develops due to consistently high blood sugar. It usually develops 10 years after a type 1 diabetes diagnosis, but patients with type 2 diabetes can have this disease when they first show up to the doctor.

You’ll come across different terms when referring to kidney disease in diabetes, including:

• Chronic kidney disease (CKD): This is defined as an abnormality of kidney structure and function that persists for more than three months. Common causes include diabetes (where it’s known as diabetic kidney disease), high blood pressure, and autoimmune kidney diseases.

• End-stage renal disease (ESRD). This is defined as irreversible kidney dysfunction with a glomerular filtration rate (GFR) of less than 15 . The GFR is an estimate of how much blood your kidneys can filter per minute, which indicates how well the kidneys are working. Any cause of CKD can lead to ESRD if not treated, including diabetes.

Diabetic nephropathy develops because high blood sugar leads to a process where the walls of kidney blood vessels get sugar molecules attached to them, which prevents them from functioning properly.

Over time, these blood vessels become stiff due to excess sugar and are unable to filter blood adequately.

The kidney senses this decline in function and grows bigger to compensate for it. But the new growth is often abnormal and contains scar tissue, which doesn’t have the same cellular structure of normal kidney tissue, rendering it nonfunctional.

Diabetic nephropathy patients don’t usually show any symptoms during the early stages of the disease. Some may report foamy urine, but that’s about it.

As the disease progresses and kidney function starts to decline significantly, patients develop:

• High blood pressure : The kidneys play an important role in maintaining normal fluid levels in the body. When they can’t excrete excess water, it builds up inside the blood vessels and increases blood pressure.

• Peripheral edema : This is when excess water pools under the skin. Patients develop a puffy face and swollen hands and feet.

• Pulmonary edema : This is when the excess water inside the body starts pooling around the lungs. It leads to shortness of breath, cough, increased breathing rate, and low oxygen levels.

• Heart failure : If there’s too much water inside the body, the heart has to work harder to pump it around. This exhausts the heart and patients start showing signs of heart failure, such as shortness of breath on lying down, constant fatigue, and cold hands and feet.

There are also many symptoms that occur due to the accumulation of toxic substances that kidneys normally flush out. Patients in this condition are said to be in a “uremic state,” whose symptoms include:

• Itching

• Fatigue

• Weakness

• Headaches

• Hand tremor

• Loss of appetite

• Skin color changes

• Nausea and vomiting

• Ammonia- or urine-like breath odor

• Tingling in hands and feet due to nerve dysfunction

• Altered consciousness levels, where patients become disoriented

• White blood cell dysfunction, which increases the risk of infection

• Increased bleeding tendency caused by abnormal platelet function

• Uremic frost: kidney dysfunction leads to high levels of urea secreted in the sweat, the evaporation of which results in tiny crystallized yellow-white urea deposits on the skin.

• Seizures

• Coma

There are five stages of diabetic nephropathy based on the glomerular filtration rate :

• Stage 1: GFR > 90

• Stage 2: GFR 60 - 89

• Stage 3: GFR 30 - 69

• Stage 4: GFR 15 - 29

• Stage 5 (Kidney Failure): GFR < 15

Higher stages have poorer outcomes, meaning patients are more likely to die or develop complications. They also mean patients need to be monitored more frequently than those with lower-stage disease.

The diagnosis of diabetic nephropathy begins with regular screening for the condition. All diabetes patients with a glomerular filtration rate greater than 60 are screened once a year, while those with a lower filtration rate are screened more frequently.

The screening is done by checking urine albumin levels and calculating the glomerular filtration rate. If the kidneys are functioning well, there should be no albumin (a protein) in the urine because it’s too large to pass through kidney blood vessels.

If someone comes out to be positive on these screening tests, the next step is confirmatory testing via:

• Laboratory studies showing persistent (≥ 3 months) albumin in the urine and a glomerular filtration rate under 60.

• Exclusion of alternative causes of kidney disease, such as high blood pressure and autoimmune kidney damage.

Some patients may also need to be referred to kidney specialists for a kidney biopsy, where tissue from the kidney is cut out and examined under a microscope. These cases include:

• Unclear diagnosis

• Rapidly increasing urine albumin levels

• A glomerular filtration rate that is rapidly decreasing

• Active urinary sediment, which means the urine contains damaged kidney cells that got flushed out

• Nephrotic syndrome, which is an autoimmune kidney condition where you start losing proteins in the urine

• Patients with abnormally high blood potassium levels, low blood pH, or symptoms of fluid overload such as heart failure

Diabetic nephropathy is treated by a multidisciplinary team, which has a nephrologist (kidney doctor), endocrinologist (diabetes doctor), dietitian, and exercise specialist on board.

There are three main aspects of treatment:

There are no medicines that can reverse kidney damage, so treatment involves a wide range of measures such as:

• Ensuring appropriate fluid intake : Too much fluid will lead to overload, while too little will cause dehydration. The kidneys can’t tolerate either, so it’s important to ensure appropriate fluid intake.

• Restricting dietary protein : Diabetes patients should eat no more than 0.6–0.8 g/kg/day of protein . Restricting protein intake reduces the chances of kidney failure and death.

• Reducing sodium intake to less than 2.3 g/day : This keeps the blood pressure in control and prevents the loss of protein in the urine.

• Adjusting potassium and phosphorus intake : The kidneys play an important role in managing the levels of these electrolytes, which has to be done manually when the related enzymes aren’t working the way they should.

• Vitamin D supplementation : The kidneys normally activate vitamin D. When they can’t, patients are more likely to experience bone pain and fractures. Vitamin D supplementation prevents that.

• Adjusting doses of any renally-cleared medications : Many drugs – such as metformin and digoxin – are excreted by the kidney. When the kidneys begin to fail, the doses of these drugs have to be reduced to prevent abnormal accumulation in the blood.

• Renal replacement therapy (RRT) if someone experiences volume overload, low blood pH, or abnormally high potassium levels despite medical treatment. RRT can be given by either dialysis (where the blood is filtered through a machine) or kidney transplant.

These measures are aimed at providing kidneys with an optimal working environment and compensating for the functions they are unable to perform.

High blood sugar is the root cause of diabetic nephropathy, so controlling it slows down the rate of kidney damage. Three important considerations include:

• Patients with diabetic nephropathy should have a glycosylated hemoglobin (HbA1C) of less than 6.5-8% , and it should be measured twice a year. HbA1C tells you the average blood sugar concentrations over the last three months and is a marker of how well the condition is controlled. Sticking to your oral diabetes drugs or insulin injections is also crucial.

• Your insulin dose might need to be reduced if you have type 1 diabetes with kidney damage. A high insulin dose in such cases can lead to abnormally low blood glucose, leading to dizziness, unconsciousness, and even coma.

• If you have type 2 diabetes and kidney disease, your doctor might change your diabetes medication to an SGLT-2 inhibitor. Examples include dapagliflozin and empagliflozin, which have been shown to reduce the progression of CKD.

High blood pressure increases the severity of kidney damage in diabetic nephropathy. If you have it, you’ll likely be prescribed an angiotensin-converting enzyme inhibitor (like captopril) or an angiotensin receptor blocker (like valsartan).

These are given at the maximum dose you can tolerate. Side effects include swelling, dry cough, high blood potassium, and skin rash.

A high-risk lifestyle leads to diabetes . Lifestyle modifications play a major in improving blood sugar control, which prevents further damage to the kidney. Recommendations include:

Diabetes patients should measure their body mass index every year. It tells you whether your weight is appropriate for your height.

If you have type 2 diabetes and are overweight, you should aim for a minimum of 5% weight loss . The more weight you can lose, the better your blood glucose levels will be.

For those with a BMI of greater than 27, weight-reducing drugs are a good option. Orlistat is one example, which prevents the absorption of fat in the intestines.

If your BMI is greater than 30, your healthcare provider might recommend bariatric surgery. This is where the size of the stomach is reduced or a section of the intestines is bypassed, so patients feel full quicker.

Physical activity not only helps you lose weight, but it also keeps the heart healthy and improves overall sugar control. Exercise recommendations for diabetes patients include:

• Two and a half hours of aerobic exercise spread over three or more days per week. Examples of aerobic exercise are swimming, jogging, and cycling.

• Two to three sessions of resistance exercise per week. This is where you exercise a muscle group against external resistance.

You also want to reduce the time you stay stationary. For example, you can get up from your desk and move around every 30 minutes and increase activities like walking, gardening, and housework in your daily routine.

Diabetic nephropathy commonly occurs with other long-term diabetes complications – especially diabetic retinopathy (eye disease) – so screening for them is part of the treatment.

Diabetic retinopathy is screened for by conducting a comprehensive eye exam. An eye specialist might also take photographs of your retina to look for abnormalities.

Screening can begin within five years after a type 2 diabetes diagnosis . But for type 1 diabetes, it starts right at the time of diagnosis. In both cases, the screening interval is one year.

Diabetic nephropathy stems from high blood sugar. This means as a patient, the most important step you can take to reduce your risk of diabetic kidney disease is ensuring good blood sugar control.

If you find regular insulin injections too painful or if you suffer from needle-phobia, you can shop for an InsuJet needle-free injector so it’s easier to maintain your insulin regimen.