The Danish national study will be presented at the Annual Congress of the European Association for the Study of Diabetes, scheduled in Milan from 28 September to 2 October
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Those who suffer from diabetes are at greater risk of getting cancer. This is stated by a national study presented at the annual Congress of the European Association for the Study of Diabetes (Easd), scheduled in Milan from 28 September to 2 October, according to which people with type 2 diabetes have an increasingly greater probability of getting cancer. “Over the past 25 years, cancer incidence has increased the most among those with diabetes 2, driven largely by obesity-related cancers,” the authors say, and “the gap has widened in recent years.”
A growing incidence
According to the research, based on data from the entire adult population of Denmark, between 2010 and 2022 the incidence of cancer among those with type 2 diabetes is 12% higher among men and 22% higher among women. In the period from 1996 to 2009, the differences in cancer incidence "were 9% and 15%" greater, respectively, for male and female diabetics compared to non-diabetics. “Our findings highlight the growing cancer burden among people with type 2 diabetes and highlight the need to prioritize cancer prevention and early diagnosis in long-term diabetes care,” says study leader Tinne Laurberg, Steno Diabetes Center Aarhus - Aarhus University Hospital. “This is particularly important for common obesity-related cancers, such as colorectal cancer and post-menopausal breast cancer, for which screening programs already exist in many countries,” he adds. “We need to ensure that people with type 2 diabetes can fully benefit from these established programs by encouraging greater participation.”
Cancer is the leading cause of death among people with type 2 diabetes
The scientists explain that due to factors such as prolonged exposure to high blood sugar and insulin levels, as well as insulin resistance and chronic inflammation, the correlation between the two diseases is such that over the last decade cancer has become the leading cause of death among people with type 2 diabetes in Denmark and other high-income countries. It is therefore essential to understand how the incidence of different types of cancer has varied over time, but population-level data on long-term trends in the incidence of cancer in people with and without diabetes 2 are scarce and the Danish team wanted to fill this gap.
The methodology of the study
The researchers used data from national health registers to compare the occurrence of new cancers - both obesity-related and unrelated - in over-18s living in Denmark between 1996 and 2022, distinguishing between those who had type 2 diabetes (T2D) and those who did not. Participants were considered non-diabetic until diagnosed with T2D, after which they were classified as having the disease. The observation period starts from the age of 18, immigration to Denmark or 1 January 1996 (whichever occurred last) and continues until cancer diagnosis, emigration, death or 31 December 2022. Over the 27 years of follow-up, 75,540 cases of primary cancer were identified among people with type 2 diabetes and 635,323 among those without.
The results for the various neoplasms
The higher incidence of cancer among diabetics was more evident for cancers linked to obesity: in the period 2010-2022, the rate was 45% higher in men and 30% higher in women compared to those without diabetes, compared to +34% and +23% respectively in the period 1996-2009. The observed trends vary significantly based on gender and type of tumor, the scientists point out. Among the most common obesity-related cancers, post-menopausal breast cancer - the most common cancer among women - recorded an 8% higher incidence in women with T2D in the period 2010-2022. Similarly, colorectal cancer, the third most frequent neoplasm in both sexes, showed a higher incidence of 17% in men and 14% in women with T2D.
As for forms of cancer not classified as associated with obesity, prostate cancer - the most common among men - recorded a 19% lower incidence in men with diabetes compared to those without diabetes in the period 2010-2022. On the contrary, in the same period the incidence of lung cancer - the second most common neoplasm in both sexes - was 23% higher in men and 25% higher in women with T2D. The difference appeared particularly marked in women: between 1996 and 2009 the incidence was 12% lower in patients with T2D compared to those without diabetes, while in the period 2010-2022 it was 25% higher.
The objective of the study
The authors clarify that the study was designed to describe differences in cancer incidence between people with and without type 2 diabetes, rather than to determine whether diabetes itself causes them. Evaluating factors that might 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 work. The researchers also point out that classifying a tumor as 'obesity-related' reflects a consolidated association with obesity at a population level, but does not imply that obesity explains the differences in the incidence of cancer found between people with and without type 2 diabetes. The final message, however, does not change: "These results - comments Laurberg - support the need to better recognize cancer as one of the main long-term complications of type 2 diabetes. The prevention of cardiovascular diseases and Kidney disease remains a key priority in diabetes management. However, as outcomes for these complications improve, cancer may require greater attention in the long-term care setting for people with type 2 diabetes." From this perspective, suggests the expert, "our data underline the importance of integrating the prevention and early diagnosis of tumors into the consolidated aspects of diabetes care, in particular for common neoplasms such as those of the colorectal, lung and breast".
