The cancer rate over time has increased for older adults with type 2 diabetes, while it has decreased for younger ages, according to a new analysis published in the journal Diabetologia.
The link between cancer and diabetes doesn’t get as much attention as other risks associated with diabetes, such as cardiovascular disease or microvascular complications (retinopathy, neuropathy, or kidney disease). This lack of discussion may reflect, in part, the complicated nature of the link between diabetes and cancer — one study, for example, found that having diabetes doesn’t affect the likelihood of breast cancer survival. But another study came to a different opposite conclusion, possibly reflecting the different outcomes seen when participants are followed for different periods of time. Diabetes has been linked to an increased risk for blood cancers, and a rise in liver cancer deaths has been linked to nonalcoholic fatty liver disease (NAFLD), which is closely tied to type 2 diabetes. Higher daily insulin doses have also been linked to a higher risk for cancer, while bariatric (weight-loss) surgery and type 2 diabetes remission are linked to a lower cancer risk. Certain dietary factors related to diabetes may also affect cancer risk — consuming more fruits and vegetables is linked to a lower cancer and overall death risk, while consuming sugary beverages is linked to an increased risk for colorectal cancer.
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For the latest analysis, researchers looked at a group of 137,804 people who were diagnosed with type 2 diabetes at an age of 35 or older between January 1998 and November 2018. During a median follow-up period of 8.4 years, the researchers looked at rates of death from all causes, death from all cancers, and death from specific types of cancer. For each of these outcomes, the researchers sorted participants by age, sex, race or ethnicity, socioeconomic status (wealth and income), obesity status, and smoking status. They also compared mortality rates with those in the general population, outside this group of participants.
Cancer burden increased in older people with diabetes
The researchers found that between 1998 and 2018, the rate of death from all causes decreased in all age groups of participants. The rate of death from all cancers decreased among participants who were 55 or 65 years old, but increased among those who were 75 or 85 years old. For 55-year-olds, the average annual change in death from all cancers was a drop of 1.4%; for 65-year-olds, it was a drop of 0.2%; for 75-year-olds, it was an increase of 1.2%; and for 85-year-olds, it was an increase of 1.6%.
Increase in cancer deaths seen in people with diabetes and obesity
The average annual change in death from all cancers was an increase of 1.5% for women, compared with an increase of 0.5% for men. For the least socioeconomically deprived participants, the average annual change was an increase of 1.5%, compared with an increase of 1.0% for the most socioeconomically deprived participants — a surprising result, since the least deprived participants presumably had better access to medical care. The average annual change was an increase of 5.8% for participants with severe obesity, compared with an increase of 0.7% for participants with a normal body weight — highlighting an alarming increase in cancer deaths among people with diabetes and obesity.
Increasing cancer mortality trends were also seen among white participants and former or current smokers, while decreasing cancer mortality trends were seen among participants of other racial or ethnic backgrounds and nonsmokers. When it came to cancer types, increasing mortality trends were seen for pancreatic, liver, and lung cancers in all age groups; for colorectal cancer in most age groups; for breast cancer in younger age groups; and for prostate and endometrial cancers in older age groups. Compared with the general population, those with type 2 diabetes in the main analysis were more than 50% more likely to die from colorectal, pancreatic, liver, or endometrial cancer.
“In contrast to the declines in all-cause mortality rates at all ages, the cancer burden has increased in older people with type 2 diabetes, especially for colorectal, pancreatic, liver and endometrial cancer,” the researchers wrote. “Tailored cancer prevention and early detection strategies are needed to address persistent inequalities in the older population, the most deprived, and smokers.”
Want to learn more about diabetes and cancer? Read “What to Know About Medullary Thyroid Cancer,” “What Is Colorectal Cancer and How Can You Lower Your Risk?,” and “Skin Cancer: Types, Risk Factors, Prevention, and More.”
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