3 min readNew DelhiJul 28, 2026 06:00 AM IST
What happens to your kidneys when blood sugar crosses 180 mg/dL? Answering this Quora query: ‘Why is the renal threshold for glucose set at 180 mg/dL, and what exactly happens to your kidneys when glucose levels reach this point?’, Dr Sumiran Mahajan, consultant nephrologist, interventional nephrology and transplant services, KIMS Hospitals Thane, noted that the kidneys filter glucose from the blood and reclaim almost all of it using special transporters in the kidney tubules.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
“These transporters can only handle a certain amount. When blood glucose approaches 180 mg/dL, they start to reach their limit. Beyond this point, the kidneys cannot reabsorb all the filtered glucose, and the excess spills into the urine. This point is known as the renal threshold for glucose,” said Dr Mahajan.
Notably, this value is not fixed for everyone; it can change depending on age, kidney function, pregnancy, and long-standing diabetes,” said Dr Mahajan.
Are you experiencing these symptoms? (Photo: Getty Images/Thinkstock)
When glucose appears in the urine, it pulls water along with it through a process called osmotic diuresis. This leads to more frequent urination. As a result, people with uncontrolled diabetes often feel the need to urinate often, experience excessive thirst, and become dehydrated. “At this point, the kidneys aren’t suddenly failing, but they are working under more stress. If high blood sugar levels continue for months or years, this ongoing burden can slowly damage the tiny filtering units of the kidneys, known as glomeruli. This raises the risk of diabetic kidney disease, which is a leading cause of chronic kidney disease worldwide,” said Dr Mahajan.
What happens to your kidneys when blood sugar crosses 180 mg/dL? (Photo: Quora)
Does crossing the 180 mg/dL threshold always indicate kidney damage?
Finding glucose in the urine shows that the kidneys’ ability to reabsorb glucose has been exceeded; it does not mean the kidneys are damaged.
“However, if blood glucose often stays above this level, it indicates poor diabetes control and increases the long-term risk of kidney injury. It’s essential to keep blood sugar levels stable through appropriate treatment, a balanced diet, regular exercise, and periodic checks on kidney health. Early intervention can greatly lower the risk of lasting kidney problems,” said Dr Mahajan.
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DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.