medwireNews: Researchers find that south Asian, Black, Chinese, and Arab minority groups living in the UK have an increased risk for type 2 diabetes at markedly lower BMI thresholds than the majority White population.
And by virtue of having ethnicity data on 1,472,819 adults with no previous diagnosis of diabetes, the team was able to delve into ethnic subgroups, revealing further variation within.
The study participants, whose data came from the UK’s Clinical Practice Research Datalink, were predominantly White (90.6%), but 5.2% were south Asian, 3.4% were Black, 0.7% were Chinese, and 0.2% were of Arabic descent.
During a median follow-up of 6.5 years, 6.6% of these people received a diagnosis of type 2 diabetes, with people from ethnic minority groups receiving their diagnoses at a younger median age than their White counterparts, at 54–60 versus 67 years.
At a BMI of 30.0 kg/m2, White people had an age- and sex-adjusted incidence of diabetes of around 10 per 1000 person–years. But diabetes developed at this same incidence at a markedly lower BMI in the ethnic minority groups, with the lowest of 23.9 kg/m2 seen in south Asians.
The equivalent BMI cutoffs for the other ethnic groups were 26.6 kg/m2 in the Arab group, 26.9 kg/m2 in Chinese people, and 28.1 kg/m2 in Black people.
And these differences persisted after accounting for smoking habits and socioeconomic status, Rishi Caleyachetty (University of Oxford, UK) and co-workers report in The Lancet Diabetes & Endocrinology.
Dividing the south Asian and Black ethnic groups into subgroups revealed more variation, with the BMI cutoff equivalent to 30.0 kg/m2 in White people ranging from 21.2 kg/m2 in Bangladeshi people to 24.3 kg/m2 in Indian and Nepali people, and from 26.0 kg/m2 in Black Caribbean people to 29.9 kg/m2 in Black British people.
The pattern was the same for diabetes incidence at the BMI cutoff of 25.0 kg/m2 used to define overweight in White people, with the equivalent threshold in the ethnic minority groups ranging from 19.2 kg/m2 in south Asians to 23.4 kg/m2 in Black people.
In a linked commentary, David Cummings (University of Washington, Seattle, USA) and Francesco Rubino (King’s College London, UK) say the findings “warn against using uniform BMI cutoffs for the screening and prevention of type 2 diabetes,” and also for determining who gets obesity therapies including surgery.
They write: “It is becoming increasingly clear that, as a measure of obesity, BMI has many serious shortcomings, regardless of whether we consider obesity as a risk factor for future disease or as a disease per se.”
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Lancet Diabetes Endocrinol 2021; doi:10.1016/S2213-8587(21)00088-7
Lancet Diabetes Endocrinol 2021; doi:10.1016/S2213-8587(21)00122-4