With high glucose levels come painful kidney stones

Chronic diabetes is known to increase the risk of developing kidney stones by up to twofold.

“High glucose levels cause high blood viscosity and lead to frequent urination,” says Dr Mahesh DM, consultant, endocrinology, Aster CMI Hospital, Bengaluru. “People lose more water through urine, leading to dehydration, which is one of the major contributors of kidney stones. That is why we advise those with kidney stones to drink a lot of water.”

Dr Mahesh adds that the basic alkaline nature of urine is to prevent the formation of stones. There are usually four types of kidney stones:

• calcium oxalate
• uric acid
• struvite
• cystine.

“But due to high glucose levels, the body will start producing ketoacids that will increase acidity in the urine,” Dr Mahesh says. “Acidic urine increases the risk of kidney stones.”

Diabetes and kidney stones

According to a study — ‘Does chronic hyperglycaemia increase the risk of kidney stone disease? results from a systematic review and meta-analysis’ — published in BMJ Open in 2020, glycemic control and insulin resistance are the two most important factors in the formation of kidney stones.

Hyperglycemia was found to increase urinary calcium, phosphorous, uric acid and oxalate secretion that could lead to the formation of kidney stones. Increased insulin resistance also contributed to urinary acidification as it ultimately decreases the citrate level, which is an alkalizing agent (citrate). Together, these mechanisms lead to increased risk of precipitation and subsequent formation of uric acid stones, says the study.

Are kidney stones common in people with diabetes?

People with diabetes usually have metabolic syndrome (group of disorders that include high BP, obesity, high cholesterol) that tend to create excess uric acid.

“Uric acid stones, which are usually rare in the general population, are common among people with diabetes,” says Dr Garima Aggarwal, nephrologist and renal transplant physician, Bengaluru. “Metabolic syndrome is associated with insulin resistance, which is known to lead to low pH and make urine acidic.”

Since people with diabetes are more prone to infections, they are also at risk of developing struvite stones and oxalate stones due to highly acidic urine.

Signs of kidney stones

The main symptoms of kidney stones are:

• Severe pain, for which there is little relief even after taking painkillers
• Frequent urination
• Urge to urinate but not much urine passes
• Infections, which can pass on to the kidney and then cause fever and chills
• Burning sensation while passing urine.

People with diabetes are prone to recurrent renal stones and renal diseases – and they get these earlier than those with no diabetes. “Chronic kidney disease is more common in diabetics and progression of renal failure will [quicken among them],” says Dr Mahesh.

Kidney stones treatment

The rate of stone formation is also faster among people with diabetes, and it is not easy to manage.

Normally, urine contains no or very little glucose. But in cases of too much glucose in the blood, the kidneys will try to pass the extra glucose through urine and it can get mixed with other molecules and water, and increase in size.

“If the stone is less than 5mm in size and lower down the ureter (tube that carries urine from kidney to bladder), then it can sometimes be managed with medicines,” says Dr Garima. “However, if the stone is up the ureter or is bigger than 5mm, then it could cause infection and require surgery.”

Diabetes and kidney stones diet

People who have renal stones are at higher risk of developing them again. Hence, they are advised to follow a kidney stone diet:

• Have plenty of water, at least three to four litres a day
• Consume more fresh vegetables and fruits
• Avoid food with high oxalate (such as chocolates, kidney beans, beetroot, spinach and potato) since they tend to cause more stone formation
• Consume non-vegetarian food in moderation since animal protein makes the urine more acidic
• Avoid junk food
• Avoid unprescribed vitamin C and D supplements since they are associated with more recurrence of stones. 

How to prevent kidney stones if diabetic

• Keep hydrated
• Maintain glucose levels under control
• Ensure intake of medications on time as prescribed by doctor
• Lose weight if obese.

Takeaways

Diabetes increases twofold the risk of developing kidney stones. People with diabetes lose more water through urine, leading to dehydration, which could aid in the formation of kidney stones. High glucose levels also make urine acidic, increasing the risk of kidney stones. Kidney stone symptoms include severe pain, frequent urination and burning sensation during urination. Experts recommend lifestyle and dietary modifications along with good diabetes control to prevent recurring episodes.