Cardiometabolic disease and cancer. Effects of body weight and diabetes

Abstract

Background: The rise in overweight and obesity rates is associated with an increase in various forms of cardiovascular disease (CVD) and cancer. Moreover, an increasing proportion of young people with diabetes have type 2 rather than type 1 diabetes, and the extent to which the two types differ with respect to future CVD risk has not been established. Type 2 diabetes may confer a higher excess risk of CVD in women compared to men. Aims and methods: This thesis aimed to evaluate the association between body mass index (BMI) in young women and the risk of acute myocardial infarction (AMI), ischemic stroke, and mortality (Study I), the relation between BMI in young women and the risk of obesity-related cancers (Study II), the potential differential effects of type 1 and type 2 diabetes on the risk of CVD and mortality (Study III), and sex differences in the excess risk of AMI, ischemic stroke, heart failure, and death among patients with type 2 diabetes (Study IV). The cohort of young women in study I and study II was derived from the Swedish Medical Birth Register, which was linked to the National Patient Register (NPR), and the Cause of Death Register. In Study III and Study IV, we used data from the National Diabetes Register and the NPR. Incidence rates and Cox proportional hazards models were used to study the outcomes. Results: The hazards of AMI, ischemic stroke and CVD mortality increased with increasing BMI with the highest rates in those with severe obesity (Study I). Higher BMI, compared to the reference low-normal BMI, was associated with increased hazards of endometrial, ovarian, colorectal, kidney, gallbladder, esophageal cancer, and obesity-related cancer mortality (Study II). Comparing type 1 and type 2 diabetes, young patients with type 2 diabetes had a higher risk of cardiovascular outcomes, while among older patients, those with type 1 diabetes had a higher risk of these outcomes compared to patients with type 2 diabetes (Study III). Among individuals with type 2 diabetes, young women had a higher excess risk of AMI compared to young men; sex differences in the excess risk of ischemic stroke, heart failure, and all-cause mortality were less pronounced (Study IV). Conclusions: With the increasing rates of overweight and obesity in young women, our findings indicate the need of preventive strategies and early management to reduce the risk of CVD, obesity-related cancers, and mortality. Early screening for type 2 diabetes in young adults, particularly those with overweight and obesity is crucial.