Living to 100 was once extraordinary, but it’s becoming more common—prompting scientists to ask whether clues to exceptional longevity might appear decades earlier in routine blood tests. A large Swedish study explored this idea by tracking tens of thousands of people and examining whether everyday lab markers could help explain who ultimately reached very old age.

Researchers investigated whether blood results taken in midlife—such as glucose, cholesterol, and indicators of organ function—were linked to surviving beyond 90 or even 100 years. They compared individuals who later became centenarians with those who did not, all of whom had been tested at roughly the same age. With follow-up periods stretching up to 35 years, the study offered rare insight into long-term health patterns.

The analysis drew on the AMORIS cohort, a large database from Stockholm County containing detailed laboratory data. In total, 44,636 participants born between 1893 and 1920 were included. Over time, 1,224 of them reached age 100, most of whom were women. National health registers allowed researchers to reliably track medical histories and causes of death, strengthening the findings.

Twelve common blood markers were examined, including glucose, total cholesterol, creatinine, liver enzymes, albumin, iron levels, total iron-binding capacity, and uric acid. Researchers later clarified an important detail: it was low cholesterol—not high cholesterol—that was associated with lower chances of reaching 100. Extremely low iron levels were also linked to reduced longevity.

Blood sugar stood out as one of the strongest predictors. Participants with the highest glucose levels had the lowest likelihood of becoming centenarians, echoing long-established links between elevated blood sugar, cardiovascular disease, and accelerated aging.

Measures of kidney and liver health were also significant. Higher creatinine levels and elevated liver enzymes were associated with lower odds of exceptional longevity, suggesting that long-term stress on these organs may shorten lifespan.

Uric acid showed a clear pattern as well. Lower levels were tied to a greater chance of living to 100, possibly reflecting lower chronic inflammation—an important factor in healthy aging.

Taken together, the findings suggest that balance matters. Extremely high or very low values in common blood tests were generally associated with reduced odds of reaching 100. While no single test can predict how long someone will live, the study highlights the importance of maintaining stable metabolic health and organ function over time as key contributors to longevity.