Reaching the age of 100 used to be quite a rare achievement. Yet, nowadays, it seems to be a rather commonplace occurrence. Well, believe it or not, centenarians are not the fastest-growing demographic age group worldwide. Researchers in Sweden followed tens of thousands of people and analyzed routine blood tests taken years earlier. They then posed a question regarding the potential link between blood type and longevity. Do common lab markers hint at who reaches 100 years of age? The study revealed some of those common biomarkers, including glucose and cholesterol levels, in individuals who live past 90. The work has been published in a respected journal and made use of linked national registers; therefore, it draws on strong data. In this article, we will walk through what they measured and how they analyzed it.The team wanted to know whether simple blood tests, collected many years earlier, relate to exceptional longevity. Exceptional here means living to at least 100. They compared people who reached 100 with peers who did not. The participants all had their blood tests taken when they were about the same age. This is essential, since comparing a 70-year-old with a 90-year-old can confuse any signal. The study included standard markers of metabolism, kidney and liver function, iron status, and a measure tied to inflammation. The design used a long follow-up period, which would help to strengthen the conclusions. Participants were tracked for as long as 35 years after the first blood draw, using Swedish registers that record disease, deaths, and residence.