Editorial NexoScience
Something as mundane as skipping a glass of water could be nudging the body toward diabetes years down the line. That is the striking implication of a huge cohort study out of China that followed over seventy thousand adults for more than a decade, using nothing more exotic than a routine measure of how concentrated their urine was.
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The research, published in the journal Nutrients, tracked 71,526 adults enrolled in the Kailuan cohort in Tangshan starting in 2006 and 2007, following them through 2020. People with signs of chronic dehydration developed type 2 diabetes at a meaningfully higher rate than people who stayed well hydrated. Researchers used urine specific gravity, a cheap and simple lab test that measures how concentrated urine is, as a stand in for hydration status. They sorted participants into five groups, from optimally hydrated to severely dehydrated, and then watched who went on to develop diabetes over a median follow up of more than twelve years.
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The pattern held up even after accounting for the usual suspects. After adjusting for age, sex, education, salt intake, physical activity, smoking, drinking, body mass index, blood pressure, cholesterol, kidney function and several other factors, people in the dehydrated group had a 30 percent higher risk of developing diabetes than those in the best hydrated group, and people in the severely dehydrated group had a 38 percent higher risk. The researchers also repeated the measurement at each follow up visit rather than relying only on the first reading, and found the same climbing pattern: mild, moderate and severe dehydration were tied to 16, 26 and 33 percent higher diabetes risk respectively compared with staying well hydrated.
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Men and older adults appeared to carry the biggest share of the risk. When the authors broke the results down by subgroup, the link between poor hydration and diabetes was strongest in men and in adults over 65, though it showed up across most groups tested, including smokers and drinkers.
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There is a plausible biological story behind the numbers, not just a statistical coincidence. Chronic under hydration raises levels of a hormone called vasopressin, which helps the body conserve water. Vasopressin also acts on receptors in the pancreas and liver in ways that can push up blood sugar regulating hormones like glucagon, and some earlier studies have already linked higher levels of a related marker to increased diabetes risk. The authors argue this gives a testable mechanism for why chronically concentrated urine might track with future diabetes, rather than the two simply happening to move together.
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This is an observational study, so it shows an association, not proof that dehydration by itself causes diabetes. People who habitually drink too little water may also differ in other ways the researchers could not fully measure, and the study relied on a single urine test per visit rather than tracking daily water intake directly. The authors themselves note that a Chinese cohort followed with routine clinical measurements cannot be assumed to generalize perfectly to every population, and they call for further research to confirm the relationship and test whether encouraging people to drink more water actually lowers diabetes risk in practice.
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Still, the size of the study and the consistency of the pattern across both the one time measurement and the repeated one make it hard to dismiss as noise. Given how easy and low risk it is to simply drink more water, the findings add one more reason to take that advice seriously.
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Source: Dong Y, Chen S, Yu Y, Li W, Xu Z, Du J, Huang S, Wu S, Cai Y. “Association between Urine Specific Gravity as a Measure of Hydration Status and Risk of Type 2 Diabetes: The Kailuan Prospective Cohort Study.” Nutrients, 2024;16(11):1643. DOI: 10.3390/nu16111643.
