New Diabetes After 50 Is Usually Just Diabetes. One Combination Deserves a Closer Look.

• In a population-based study of 2,122 adults aged 50 or older with newly diagnosed diabetes, 18 (0.85%, roughly 1 in 100) were diagnosed with pancreatic cancer within three years, and more than half of those within six months of the diabetes diagnosis.
• In the months before pancreatic cancer is diagnosed, blood sugar tends to rise first, about 30 to 18 months beforehand, followed by falling weight and loss of fat under the skin about 18 to 6 months beforehand.
• A risk score built from age at diabetes onset, change in blood sugar, and change in weight identified a higher-risk group in which 3.6% had pancreatic cancer, while about half of people with new diabetes scored in an extremely low-risk range.

November is Pancreatic Cancer Awareness Month, and I want to handle this one carefully, because a lot of people reading it were just told they have diabetes. So start with the reassuring part. New onset diabetes after 50 is, for the overwhelming majority of people, exactly what it looks like: ordinary type 2 diabetes, usually arriving slowly over years alongside weight gain, a less active stretch of life, and a family history. That is the pattern most people expect, and usually it is the right one. But there is one combination I never wave through. When blood sugar climbs quickly while the scale goes down and the person was not trying to lose weight, the story does not fit ordinary type 2 diabetes. Type 2 diabetes usually travels with extra weight, not with weight melting away. The reason this matters is that the pancreas makes insulin, and a tumor growing in the pancreas can disturb blood sugar before it causes pain, jaundice, or anything else a person would notice. In some people, new diabetes is the first clue that something else is going on.

The numbers are worth knowing precisely, because they are both sobering and reassuring. In a population-based study of 2,122 adults aged 50 or older with newly diagnosed diabetes, 18 people, about 0.85%, were diagnosed with pancreatic cancer within three years. That is close to eight times the expected rate, and 10 of those 18 were found within six months of the diabetes diagnosis. Put the other way, more than 99 of every 100 people in that study did not have pancreatic cancer. Later work showed the sequence. In the 30 to 18 months before pancreatic cancer was diagnosed, blood sugar rose before any measurable loss of fat or muscle; then, from about 18 to 6 months beforehand, weight and the fat under the skin fell while sugars kept rising. A cohort of nearly 1.5 million people found the same signal across racial and ethnic groups: subtle weight loss in the years before the diabetes diagnosis and a faster rise in glucose and A1c. A risk score combining age at onset, the change in blood sugar, and the change in weight flagged a group in which 3.6% had pancreatic cancer, while about half of people scored low enough to be at extremely low risk. That score still needs prospective testing.

Should I worry about pancreatic cancer with new onset diabetes after 50?

Mostly, no. Worry is not the right tool here, and scanning everyone is not the answer either: the U.S. Preventive Services Task Force recommends against screening adults without symptoms for pancreatic cancer, because there is no evidence it saves lives and the harms are real. What I want instead is attention to one pattern. If your sugar goes up while your weight goes down without trying, I don't want to just add metformin and move on. I want to know your weight a year ago, how fast your A1c rose, whether you were recently on steroids, which can push sugars up, and whether anything else has changed in how you feel. Weight you lost on purpose after the diagnosis, because you started walking and cut back on sugar, is the treatment working, and it is not the pattern I mean. The weight that matters is the weight that left before you changed anything. So before your next diabetes visit, look back at your weight over the past year, from a bathroom scale, an old visit summary, or how your clothes fit, and say it out loud to your doctor. Diabetes plus weight you didn't try to lose is a conversation, not a coincidence.

References

1. Chari, S. T., Leibson, C. L., Rabe, K. G., Ransom, J., de Andrade, M., & Petersen, G. M. (2005). Probability of pancreatic cancer following diabetes: A population-based study. Gastroenterology, 129(2), 504-511.
2. Sah, R. P., Sharma, A., Nagpal, S., Patlolla, S. H., Sharma, A., Kandlakunta, H., et al. (2019). Phases of metabolic and soft tissue changes in months preceding a diagnosis of pancreatic ductal adenocarcinoma. Gastroenterology, 156(6), 1742-1752.
3. Huang, B. Z., Pandol, S. J., Jeon, C. Y., Chari, S. T., Sugar, C. A., Chao, C. R., et al. (2020). New-onset diabetes, longitudinal trends in metabolic markers, and risk of pancreatic cancer in a heterogeneous population. Clinical Gastroenterology and Hepatology, 18(8), 1812-1821.e7.
4. Sharma, A., Kandlakunta, H., Nagpal, S. J. S., Feng, Z., Hoos, W., Petersen, G. M., & Chari, S. T. (2018). Model to determine risk of pancreatic cancer in patients with new-onset diabetes. Gastroenterology, 155(3), 730-739.e3.
5. Owens, D. K., Davidson, K. W., Krist, A. H., Barry, M. J., Cabana, M., Caughey, A. B., et al. (2019). Screening for pancreatic cancer: US Preventive Services Task Force reaffirmation recommendation statement. JAMA, 322(5), 438-444.