For kidneys, diabetes holds the unbearable sweetness of being

One of the most common kidney complications seen in people with diabetes is diabetic nephropathy, commonly called diabetic kidney disease (DKD).  It is essentially chronic kidney disease (CKD) due to diabetes. Left unmanaged, it could lead to end-stage renal disease (ESRD) and kidney failure. Interestingly, medical experts have been noticing a proportionate increase and the early onset of kidney complications in recent years, due to a global increase in the number of people with diabetes, especially in the youth.

The diabetes effect on kidneys

High blood sugar damages renal blood vessels that play an important role in the filtration and expulsion of toxins from the blood through urine. Millions of tiny nephrons and blood vessels in the kidneys ensure the timely removal of toxins from the blood. 

The renal filtration unit comprises millions of microscopic nephrons having a blood filter called glomerulus attached to a tubule through which nutrients are absorbed back into the blood and kept away from urine heading towards the bladder. High blood sugar damages blood vessels attached to the tubule which should ensure that essential nutrients are not expelled. The presence of albuminin, an essential protein in urine indicates that the filtration process has been compromised.

“Leakage of albumin into the urine is the earliest sign of diabetes affecting the kidneys,” said Dr Vidyashankar P, lead consultant, nephrology, Aster CMI Hospital, Bengaluru. A healthy kidney ideally prevents albumin from passing out from blood into the urine, he added.

Diabetes also causes nerve damage around the bladder and urinary tract leading to bladder and urinary tract infections and triggering renal complications due to urine retention. Diabetes also increases blood pressure in the renal arteries.

Dr Subrata Das, senior consultant-internal medicine and diabetology, at Sakra World Hospital, said that DKD also increases the risk of diabetic retinopathy in people with diabetes. High creatinine and other waste molecules in the blood due to flawed renal filtration eventually damages optical blood vessels causing the onset of retinopathy.

“People who have retinopathy are most likely to have nephropathy as well. An annual eye test is also recommended for people diagnosed with diabetic kidney disease,” said Dr Das.

Progression of diabetic nephropathy

Estimated Glomerular Filtration Rate (eGFR) is a common yardstick to determine the extent of renal damage due to diabetic nephropathy. It is calculated using either serum creatinine level or  urine albumin to creatinine ratio (UACR)  along with factors like age and gender.  The eGFR value generally tends to decline with age. 

Albumin levels also indicate the extent of renal damage. “Less than 30 mg considered normal, if it is more than 30 mg, it indicated that there is a leak of albumin in the urine,” said Dr Das.

If DKD is accompanied by a UACR between 30 and 299 mg/g creatinine then it is called microalbuminuria whereas if UACR is in excess of 300 mg/g then it is macroalbuminuria.

Screening and essential tests for diabetic kidney disease

• Creatinine blood test

Serum creatinine tests measure creatinine in blood which is a muscular waste that should be expelled by healthy kidneys. High levels of serum creatinine indicate kidney disease. Serum creatinine value is also used to calculate the estimated glomerular filtration rate (eGFR) rate.

• Urine albumin-creatinine ratio (UACR)

This test measures albumin in the urine. Albumin is supposed to be retained in blood and expelled only minimally. If excess albumin is present in urine, it means it’s time to consult a nephrologist.

• Kidney biopsy

Kidney biopsy is also carried out in cases with extremely high protein in urine and also if the cause of renal complications cannot be identified through traditional tests and examinations. A tiny piece of kidney tissue is removed and evaluated to determine the underlying cause and severity of kidney damage. 

• Regular diabetes checkups

People diagnosed with DKD should check their HbA1c (average blood sugar) once in three months and also opt for an annual eye check-up.

Early detection and lifestyle alterations

Lifestyle alterations could improve renal functions if DKD is diagnosed at the onset itself. Dr Vidyashankar recalls the case of a 42-year-old man, diagnosed with diabetes and DKD in 2020. He was prescribed medication for protein leakage in his urine.

“He was also asked to make lifestyle modifications like quitting smoking, reducing salt intake etc. He is doing fine now,” he added

Dr Das also said that physical activity and dietary control should be made a top priority for people with diabetes to manage blood sugar and pressure levels to manage their renal health.

Takeaways

Diabetes could trigger serious kidney complications and is often called diabetic kidney disease or diabetic nephropathy. High blood sugar triggers vascular damage in the kidneys affecting their filtration and could also induce nerve damage to the bladder and urinary tract. DKD often progresses slowly and is often diagnosed late after its onset. Experts point out that timely detection and intervention could make a huge difference in managing DKD and avoiding renal failure.