Ethnicity-specific BMI cutoffs for obesity based on type 2 diabetes risk in England: a population-based cohort study
Study (n=1,472,819) found that Black Caribbean, south Asian, Chinese, and Arab populations living in England had an equivalent risk of type 2 diabetes at substantially lower BMI values than the current BMI cutoffs for obesity set for White populations. .
Source:
The Lancet Diabetes & Endocrinology
SPS commentary:
In study, 1,333,816 (90.6%) were White, 75,956 (5.2%) were south Asian, 49,349 (3·4%) were Black, 10,934 (0·7%) were Chinese, and 2764 (0·2%) were Arab. After a median follow-up of 6·5 years, 97 823 (6·6%) of 1,472,819 individuals were diagnosed with type 2 diabetes. For the equivalent age-adjusted and sex-adjusted incidence of type 2 diabetes at a BMI of 30.0 kg/m2 in White populations, the BMI cutoffs were 23·9 kg/m2 in south Asian populations, 28.1 kg/m2 in Black populations, 26·9 kg/m2 in Chinese populations, and 26·6 kg/m2 in Arab populations.
A commentary discusses the limitations of the study including that these ethnicity-specific BMI cutoffs apply only to the risk of developing type 2 diabetes, and might not apply to other obesity-related comorbidities, cardiovascular disease risk factors, cancer, or mortality. In addition, the metric used for obesity was BMI, which is flawed compared with the more nuanced, although less practical, measures of body fat composition and distribution. Also the Chinese (0·7% of the study population) and Arab (0·2% of the study population) subgroups in the trial were small, which might have resulted in misestimation of their BMI cutoffs related to diabetes risk. Furthermore, because diabetes and obesity are influenced by genetic and environmental determinants, BMI cutoffs for obesity related to diabetes risk among various ethnic groups living in England could reflect interactions between genetics and local environments. Despite these limitations, it suggests the study has important implications. The differences in diabetes risk-related BMI cutoffs for obesity across different ethnic groups warn against using uniform BMI cutoffs for the screening and prevention of type 2 diabetes. It also notes that it is becoming increasingly clear that, as a measure of obesity, BMI has many serious shortcomings, regardless of whether obesity is considered as a risk factor for future disease or as a disease per se.