most notably pancreatic malignancies.
“Our study demonstrates that there is an elevated risk of developing diabetes if a person is affected by lung, pancreatic, breast, brain, urinary tract, or uterine cancers,” said Lykke Sylow, PhD, associate professor in the Molecular Metabolism in Cancer and Ageing Group at the University of Copenhagen, in a statement.
“It is great to see such a large, well-designed study confirm the findings of previous smaller studies and observations,” said Elias S. Siraj, MD, the David L. Bernd Distinguished Chair for EVMS-Sentara Cardiovascular Diabetes Program at Eastern Virginia Medical School in Norfolk, when asked for comment by this news organization. Dr. Siraj also noted that “in clinical care we do observe that many patients develop diabetes after being diagnosed with cancer although one needs a well-designed study to confirm that observation.”
Diabetes risk highest with pancreatic cancer
Type 2 diabetes at the time of cancer diagnosis is known to increase cancer-specific and all-cause mortality, but not much is known about whether cancer is a risk factor for type 2 diabetes, the researchers state in their study, published in Diabetes Care.
Dr. Sylow and colleagues from the Steno Diabetes Center Copenhagen, Rigshospitalet, analyzed a database consisting of 112 million blood samples from 1.3 million Danes from 2000 to 2015. They looked at cancer cases with an incidence of more than 1,000 and excluded individuals with diabetes prior to cancer diagnosis.
They found an increased risk of new-onset type 2 diabetes for all cancers (hazard ratio, 1.09; 95% confidence interval, 1.03-1.14). For pancreatic cancer, the hazard ratio rose to 5.0 (95% CI, 3.62-6.90), for brain and nervous system cancers the hazard ratio was 1.54 (95% CI, 1.22-1.95), and for uterine cancer the hazard ratio was 1.41 (95% CI, 1.10-1.84).
The link with pancreatic cancer was not surprising, said Dr. Sylow.
Dr. Siraj agreed, noting that a few studies have shown a strong association. “It has also been observed for years that many patients with pancreatic cancer may present with new-onset diabetes,” he said. “The mechanism is not clearly understood but could include a direct damage of the beta cells by the pancreatic cancer or could be due to a paraneoplastic secretion of special factors by the cancer that can affect beta-cell function or insulin resistance,” said Dr. Siraj, who is also professor and chief of endocrinology and director of the Strelitz Diabetes Center at Eastern Virginia Medical School.
The higher diabetes risk associated with brain and nervous system cancers has not been previously described and is “an intriguing finding,” he said.
In their statement, the Danish investigators said there is nothing in their research to suggest why some cancers are associated with a higher risk of new-onset type 2 diabetes, but they offered some theories, including that chemotherapeutics and perhaps the cancer, itself, may contribute.
“We know that cancer cells are able to secrete substances that can affect organs and possibility contribute to an increased incidence of diabetes,” said Dr. Sylow in the statement.