Cancer gap widens between people with and without type 2 diabetes

People with type 2 diabetes face a higher risk of developing cancer than those without the condition, and the difference has grown wider over the past 25 years, according to a nationwide Danish study being presented at the Annual Meeting of the European Association for the Study of Diabetes (EASD) in Milan, Italy (Sept 28 – Oct 2). The research, based on data from the entire adult population of Denmark, found that cancer incidence rose more steeply among people with type 2 diabetes than among those without diabetes, with the increase largely driven by obesity-related cancers.

In the most recent period studied, 2010 to 2022, overall cancer incidence was 12% higher among men with type 2 diabetes and 22% higher among women with type 2 diabetes compared with people without diabetes. The corresponding differences in the earlier period, 1996 to 2009, were 9% for men and 15% for women, showing that the gap between the two groups has widened over time.

“Our findings underline the growing cancer burden among people with T2D and highlight the need to prioritise cancer prevention and early detection as part of long-term diabetes care,” said Dr Tinne Laurberg from Steno Diabetes Center Aarhus, Aarhus University Hospital in Denmark, who led the research. “This is especially important for common obesity-related cancers, such as colorectal and postmenopausal breast cancer, for which screening programmes already exist in many countries. We must ensure that people with T2D benefit fully from these established programmes by encouraging greater participation.”

The study drew on nationwide health registries to compare the occurrence of new obesity-related and non-obesity-related cancers among adults aged 18 and over living in Denmark between 1996 and 2022. Participants were considered to have no diabetes until they were diagnosed with type 2 diabetes, after which they were classified as having the condition. Follow-up began when participants turned 18, immigrated to Denmark or on 1 January 1996, whichever occurred later, and continued until they were diagnosed with cancer, emigrated, died or reached 31 December 2022.

During 27 years of follow-up, 75,540 first cancers were identified among individuals with type 2 diabetes and 635,323 among individuals without diabetes. The higher incidence among people with diabetes was particularly evident for obesity-related cancers, which were 45% higher in men and 30% higher in women with type 2 diabetes compared with those without diabetes in 2010 to 2022. In the earlier period, 1996 to 2009, the corresponding differences were 34% and 23%.

Patterns differed substantially by sex and cancer type. Among the most common obesity-related cancers, postmenopausal breast cancer, the most common cancer among women, had an 8% higher incidence in women with type 2 diabetes in 2010 to 2022. Colorectal cancer, the third most common cancer in both sexes, had a 17% higher incidence in men and a 14% higher incidence in women with the condition.

Common cancers not classified as obesity-related showed different patterns. Prostate cancer, the most common cancer among men, had a 19% lower incidence among men with type 2 diabetes compared with those without diabetes in 2010 to 2022. In contrast, lung cancer, the second most common cancer in both sexes, was 23% higher in men and 25% higher in women with type 2 diabetes during this period. The change over time was particularly notable in women: lung cancer incidence was 12% lower among women with type 2 diabetes than among those without diabetes in 1996 to 2009, but 25% higher in 2010 to 2022.

The researchers emphasise that the study was designed to describe differences in cancer incidence between people with and without type 2 diabetes, rather than to determine whether type 2 diabetes itself causes these differences. Assessing factors that may contribute to the observed differences and their changes over time, such as body weight, smoking, alcohol consumption and physical activity, was beyond the scope of the study. They also note that classifying a cancer as obesity-related reflects an established association with obesity at the population level and does not mean that obesity itself explains the differences observed between the two groups.

Background to the research notes that cancer is a major health condition associated with type 2 diabetes, with prolonged exposure to high blood sugar and insulin levels, as well as insulin resistance and ongoing inflammation, potentially contributing to cancer development. Over the past decade, cancer has become the leading cause of death among people with type 2 diabetes in Denmark and other high-income countries, yet population-level data on long-term cancer incidence trends in individuals with and without the condition have been scarce.

“These findings support greater recognition of cancer as a major long-term complication of T2D,” said Dr Laurberg. “Cardiovascular and kidney disease prevention remains a key priority in diabetes care. However, as outcomes for these complications improve, cancer may require greater attention as part of the long-term care of people with type 2 diabetes. Our results underline the importance of considering cancer prevention and early detection alongside other established aspects of diabetes care, particularly for common cancers such as colorectal, lung, and breast cancer.”

Subject of Research: Long-term trends in cancer incidence among people with and without type 2 diabetes in Denmark

Article Title: Cancer incidence remains higher in people with type 2 diabetes, with the gap widening in recent years

Article References: Cancer incidence remains higher in people with type 2 diabetes, with the gap widening in recent years. Original publication (Bibliographic details unavailable.)

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DOI: Not provided

Keywords: type 2 diabetes, cancer incidence, obesity-related cancers, colorectal cancer, breast cancer, lung cancer, prostate cancer, Denmark, EASD, epidemiology, diabetes complications, cancer screening