Body fatness, commonly approximated by body mass index (BMI), is an established risk factor for type 2 diabetes (T2D) and several cancer types. The International Agency for Research on Cancer (IARC) listed 13 cancers where there is sufficient evidence for causal association between increased body fatness and incident risk. Body mass index is often elevated at type 2 diabetes (T2D) diagnosis. In the BACARDI study, we used latent class trajectory modelling (LCTM) of BMI and examined whether weight loss after diagnosis influenced cancer incidence and all-cause mortality.
To do this, from 1995-2010, we identified 7708 patients with T2D from the Salford Integrated Record database (UK) and linked to the cancer registry for information on obesity-related cancer (ORC), non-ORC; and all-cause mortality. Repeated BMIs were used to construct sex-specific LCTMs.
Four sex-specific BMI trajectories were identified; stable-overweight, stable-obese, obese-slightly-decreasing and obese-steeply-decreasing including 41%, 45%, 13%, and 1% of women, and 45%, 37%, 17%, and 1% of men, respectively. In women the stable-obese class had similar ORC risks as the obese-slightly-decreasing class, whereas the stable-overweight class had lower risks. In men the obese-slightly-decreasing class had higher risks of ORC (HR=1.86, 95% CI: 1.05-3.32) than the stable-obese class, while the stable-overweight class had similar risks No associations were observed for non-ORC. Compared to the stable-obese class, women (HR=1.60, 95% CI: 0.99-2.58) and men (HR=2.37, 95% CI: 1.66-3.39) in the obese-slightly-decreasing class had elevated mortality No associations were observed for the stable-overweight classes.
The BACARDI Study concluded that patients who lost weight after T2D diagnosis had higher risks for ORC (in men) and higher all-cause mortality (both genders) than patients with stable obesity. No information was available on whether the weight loss was intentional or not therefore the current recommendation on weight loss in patients with T2D should remain unchanged.