Obesity has a greater impact on the risk for diabetes among twins than on the risk for heart disease or death, according to a new study,”Risks of Myocardial Infarction, Death, and Diabetes in Identical Twin Pairs With Different Body Mass Indexes,“ developed by researchers from Umeå University, Sweden, and colleagues.
The study was published in the journal JAMA International Medicine.
In past decades, obesity in the Western world has increased in up to 50%. Given that high body mass index (BMI) increases the risk of diabetes, cardiovascular diseases, stroke, and death, a marked increase in deaths have been attributed to obesity-related. But whether genetics influences the association between obesity, diabetes, and cardiovascular disease, was largely undetermined.
In the study, the authors used genetically identical twins to provide a unique tool for the evaluation of the risk associated with obesity independent of genetic factors. If differences in the incidence of specific diseases were evident, the disease could be attributed to genetic factors.
The study included 4,046 twin pairs, average age 57.6 years, who had differences in BMI. The participants were followed for an average 12.4 years, and assessed for the incidence of significant health events such as heart attack, diabetes, and death.
After accounting for physical activity, smoking, alcohol abuse, and educational levels, the researchers found that having a higher BMI did not increase the risk of heart attack or death. This was true, even when one of the twins was obese (with BMI higher than 30). However, elevated BMI was associated with an increased risk of diabetes. Twins with higher BMI had a 2.14 times an increase in odds for developing diabetes. In addition, increases in BMI during approximately 30 years before the study began were not associated with later risk of heart attack or death — but increased the risk of diabetes for 13% of study subjects.
The findings suggest that previously reported associations between obesity and cardiovascular disease can be explained by genetic factors, but that diabetes can be influenced by environmental factors. This means that lifestyle interventions that promote weight loss may be helpful in reducing the risk of diabetes, but might not have a great impact on the reduction of the risk of cardiovascular diseases or death.