Corresponding waist circumference and body mass index values based on 10-year absolute type 2 diabetes risk in an Australian Aboriginal community

Abstract

OBJECTIVE: There is a lack of waist circumference (WC) thresholds to identify Aboriginal individuals at high risk of type 2 diabetes. We generated gender-specific WC values with equivalent 10-year absolute risk of type 2 diabetes as body mass index (BMI) points in an Australian Aboriginal community to contribute to guidelines needed for establishing WC cut-off points for Aboriginals. RESEARCH DESIGN AND METHODS: A cohort of 803 adult participants free from type 2 diabetes in an Aboriginal community was followed up for up to 20 years. We derived WC values with absolute risks equivalent for the development of type 2 diabetes as BMI values (20-35 kg/m(2)) using the Weibull accelerated failure-time model. RESULTS: After a mean follow-up of 15.7 years, 110 participants developed type 2 diabetes. Absolute risk of type 2 diabetes increased as WC increased, ranging from 3.52% (WC=77.5 cm) to 14.14% (WC=119.9 cm) in males, and 5.04% (WC=79.5 cm) to 24.25% (WC=113.7 cm) in females. In males, WC values with same absolute risks of type 2 diabetes as BMI values were 77.5 cm for BMI=20 kg/m(2), 91.5 cm for BMI=25 kg/m(2) (overweight threshold), 105.7 cm for BMI=30 kg/m(2) (obesity threshold) and 119.9 cm for BMI=35 kg/m(2). In females, WC values were 79.5 cm for BMI=20 kg/m(2), 90.9 cm for BMI=25 kg/m(2), 102.3 cm for BMI=30 kg/m(2) and 113.7 cm for BMI=35 kg/m(2). Interaction between WC and gender was not statistically significant (p=0.53). CONCLUSIONS: The absolute risk of type 2 diabetes increased with higher WC measured at baseline screening. Males were not significantly different from females in the association between WC and type 2 diabetes. Our findings are useful contributions for future establishment of WC cut-off points for identifying high-risk individuals in Aboriginal people.