BMI Thresholds for Diabetes Screening Should Vary Across World Regions

Evidence is accumulating that the obesity epidemic has accelerated in low- and middle-income countries (LMICs). It is now estimated that 67% of people in the world with obesity and 79% of those with diabetes reside in LMICs.

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The current understanding of how body mass index (BMI) affects key clinical outcomes is based on a vast number of studies done in high-income countries. The exceptions, studies conducted in Asian and South Asian countries, prompted the lowering of the BMI thresholds that define overweight in these populations.

Jacqueline A. Seiglie, MD, MSc, an endocrinologist in the Endocrine Unit at Massachusetts General Hospital, Jennifer Manne-Goehler, MD, ScD, of the Infectious Diseases Division at Mass General, and colleagues recently characterized the risk of diabetes across the full range of BMIs in LMICs. Their report in The Lancet includes suggested optimal BMI thresholds for diabetes screening, stratified by geographic region and sex, and other recommendations for intervention.

Methods

The researchers pooled individual-level BMI and diabetes biomarker data from 58 nationally representative population-based surveys. The surveys came from 57 countries that were low-income, lower-middle-income or upper-middle-income, according to the World Bank, in the year they were conducted (2008–2019). The sample included 685,616 adults ages 25 and older.

BMI Cutoffs by Region and Sex

Based on receiver operating curve analyses, the researchers noted variability across sex and geographic regions in the optimal BMI cutoffs indicating a need for diabetes screening:

• Latin America and the Caribbean—28.3 kg/m² in women and 25.3 in men
• Europe and central Asia—28.0 and 27.6
• East, south and southeast Asia—23.9 and 23.8
• Sub-Saharan Africa—27.3 and 25.4
• The Middle East and North Africa—28.3 and 24.2
• Oceania—25.2 and 28.1

Other Key Findings

• The proportion of individuals with diabetes who had a BMI of 30 kg/m² or higher rose steeply among men in sub-Saharan Africa who were ages 25–34 and across almost all regions in the age groups 35 years and older
• BMI performed only modestly as a single criterion for determining which individuals to screen for diabetes

Suggestions for Clinicians and Policy Makers

These results imply that:

• Existing BMI cutoffs for diagnosis of metabolic risk need to be revisited in many parts of the world
• In certain regions, diabetes screening should be considered for asymptomatic adults under 40 years old, contrary to the World Health Organization guidelines, which recommend diabetes screening of asymptomatic adults with a BMI ≥25 kg/m² and who are 40 years and older
• Low-cost anthropometric measures besides BMI, such as waist circumference, might further optimize assessment of metabolic risk in LMICs

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