Optimal waist cutpoint for screening for dysglycaemia and metabolic risk: evidence from a Maori cohort

We sought to identify the sex-specific cut-off in waist circumference which best identifies those with metabolic abnormalities consistent with the metabolic syndrome (MS) among Maori, the indigenous people of New Zealand of Polynesian origin. In 3816 self-identified Maori (2742 women, 1344 men) a 75 g oral glucose tolerance test, fasting lipid, anthropometric and blood pressure measurements were made. MS components were defined by Adult Treatment Panel (ATP) III criteria. Waist cut-off was defined using receiver operating characteristic (ROC) curve analysis to define the presence of at least two of the other MS components ( > or = 2MS). Prevalence of > or = 2MS was high (42.1 %). In males and females, waist was as good, or better, a predictor of > or = 2MS (area under ROC 0.73 women, 0.68 men) as waist:hip ratio (0.66, 0.67), BMI (0.72, 0.68) or percentage body fat (0.70, 0.68). The prediction of dysglycaemia using anthropometric variables followed a similar pattern to > or = 2MS. Waist circumference to predict > or = 2MS or dysglycaemia in Maori women and men was 98 cm and 103 cm. Applying this cut-off to the International Diabetes Federation (IDF) criteria would identify 27.8 % (34.0 % males, 25.5 % females) with the MS with an OR for > or = 2MS (adjusted for sex, smoking and age) of 3.5 (95 % CI 3.1, 4.0). Age >48 years, smoking and being male increased the odds of the MS. These waist cut-offs should be considered in both clinical practice and to optimise the definition of the MS for Maori. The validity of these criteria in other Polynesian groups should be confirmed.