BMI and waist circumference cut-offs for corresponding levels of insulin sensitivity in a Middle Eastern immigrant versus a native Swedish population - the MEDIM population based study.

Background: The aim of this study was to identify corresponding body mass index (BMI) and waist circumference cut-offs for equivalent levels of insulin sensitivity in a Middle Eastern immigrant population compared with native Swedes.

Methods: Citizens of Malmö, Sweden aged 30 to 75 years, who were born in Iraq or Sweden, were in 2010-2012 invited to participate in a health examination including anthropometrics, oral glucose tolerance test, fasting samples and interviews concerning sociodemographic factors and lifestyle behaviours.

Results: In total, 1176 individuals born in Iraq and 688 born in Sweden, without previously diagnosed type 2 diabetes, participated in the study. In normal weight participants (BMI < 25 kg/m2), 21.2% of Iraqis vs 9.3% of Swedes were insulin resistant. Corresponding figures in participants without abdominal obesity (waist circumference, men < 94 cm, women < 80 cm) were 28.2% of Iraqis vs 9.4% of Swedes. The age-adjusted insulin sensitivity index (ISI) for obese Swedes (BMI 30 kg/m2) corresponded in Iraqi men with BMI of 28.5 kg/m2, and in Iraqi women with BMI of 27.5 kg/m2. The ISI level in abdominally obese Swedes corresponded with waist circumference cut-offs of 84.0 cm and 71.0 cm in Iraqi men and women, respectively. In men only, larger waist circumference (P interaction = 0.026) presented a stronger association with impaired ISI in Iraqis as compared to Swedes.

Conclusions: Our data shows that the impact of BMI and waist circumference on ISI is ethnic- and gender-specific, indicating a disturbed fat metabolism in Iraqi males in particular. Our data suggests that 10 cm lower cut-off values for abdominal obesity, than is currently recommended by major organisations, should be considered when estimating diabetes risk in Middle Eastern populations.