The optimal cutoff values and their performance of waist circumference and waist-to-hip ratio for diagnosing type II diabetes.

Studies on the theme of optimal cutoff values of waist circumference (WC) and waist-to-hip ratio (WHR) for assessing risk of type II diabetes were reviewed. Twenty-eight studies of individuals aged 18-74 years are eligible for inclusion. Four of these studies are prospective and the rest are all cross-sectional. Tongans had the highest WC (103 cm for both men and women) cutoff value (but not for WHR), followed by studies in the USA and U.K. The WC cutoff values were higher for all races in the USA and the UK studies compared with their counterparts in their original countries. The optimal WC (WHR) cutoff values were 97-99 cm (0.95) for White men and 85 cm (0.83-0.85) for White women living outside the USA and the UK, whereas they were 85 cm (0.90) for Asian men and 75-80 cm (0.79-0.85) for Asian women; the values for other ethnic groups were between those for White and Asians. Men had higher values than women in White, Chinese, Japanese, Indians and Bangladeshis, but not in Thai, Iranians, Iraqi, Tunisians, Mexicans, Africans and Tongans. At these optimal cutoff points the sensitivities were around 60-70%, which was higher or equal to the specificity. There is no universal cutoff value that can be applied worldwide, and a country-specific value should be considered taking into account the purposes and resources.

Is the association of type II diabetes with waist circumference or waist-to-hip ratio stronger than that with body mass index?

In total, 17 prospective and 35 cross-sectional studies in adults aged 18-74 years, with the aim of comparing betweenbody mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) in their relation to the incidence and prevalence of type II diabetes, were reviewed. Among these studies, only a few have used C-statistic, paired homogeneity test or log-likelihood ratio test for formally comparing the differences. Five prospective studies, in which formal statistic tests have been made, came out with inconsistent findings: two results were in favour of WC in Mexicans African Americanss, respectively, one result was in favour of BMI in Pima Indians, and no difference was found in the other 2 studies. Among the 11 cross-sectional studies that have formally tested the differences, most found a higher odds ratio or slightly larger area under the ROC curve (AUC) for WC than for BMI. A meta-analysis based on the individual data of the Asian cohorts using a paired homogeneity test showed, however, that there was no difference in odds ratio between BMI and WC in Chinese, Japanese, Indian, Mongolian and Filipino men. In conclusion, all studies included in this review showed that either BMI or WC (WHR) predicted or was associated with type II diabetes independently, regardless of the controversial findings on which of these obesity indicators is better.

Ethnic comparison of the association of undiagnosed diabetes with obesity.

OBJECTIVE: The aim of the study was to investigate the crude prevalence and estimated probability of undiagnosed diabetes in different ethnic groups, given the same level of obesity. DESIGN AND SUBJECTS: Cross-sectional data from 24 515 men and 29 952 women, aged >or=30 years, and free of previously diagnosed diabetes were included. Baseline body mass index (BMI) and waist circumference were measured. Diabetes was defined according to both fasting and 2-h 75-g glucose criteria. RESULTS: Prevalence of undiagnosed diabetes was the highest in Asian Indians, the lowest in Europeans and intermediate in others, given the same BMI or waist circumference category across the BMI or waist circumference ranges (P<0.001 for all BMI or waist categories). beta-Coefficients corresponding to a 1 s.d. increase in BMI were 0.34/0.28, 0.41/0.43, 0.42/0.61, 0.36/0.59 and 0.33/0.49 for the Asian Indians, Chinese, Japanese, Mauritian Indians and European men/women (homogeneity test: P>0.05 in men and P<0.001 in women), and in waist: 0.31/0.31, 0.30/0.46, 0.22/0.57 and 0.38/0.58 for the Asian Indians, Chinese, Mauritian Indians and Europeans, respectively (homogeneity test: P>0.05 in men and P<0.001 in women). CONCLUSION: Prevalence of undiagnosed diabetes increased with an increasing BMI or waist circumference to a similar degree in men in all ethnic groups but to a lesser degree in Asian Indian women than in others, regardless of the higher prevalence in Asian Indians than in others at the same BMI (or) waist circumference levels.

BMI compared with central obesity indicators in relation to diabetes and hypertension in Asians.

OBJECTIVE: To compare BMI with waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-stature ratio (WSR) in association with diabetes or hypertension. METHODS AND PROCEDURES: Cross-sectional data from 16 cohorts from the DECODA (Diabetes Epidemiology: Collaborative Analysis of Diagnostic criteria in Asia) study, comprising 9,095 men and 11,732 women, aged 35-74 years, of different ethnicities were included in this meta-analysis. RESULTS: Age-adjusted odds ratios (ORs) for diabetes in men (women) for 1 s.d. increase in BMI, WC, WHR, and WSR were 1.52 (1.59), 1.54 (1.70), 1.53 (1.50), and 1.62 (1.70), respectively; and the corresponding ORs for hypertension were 1.68 (1.55), 1.66 (1.51), 1.45 (1.28), and 1.63 (1.50). Paired homogeneity tests (BMI with each of the three) adjusted for age and cohort showed that diabetes had stronger association with WSR than BMI (P=0.001) in men but with WC and WSR than BMI (both P<0.05) in women. Hypertension had stronger association with BMI than WHR in men (P<0.001) and had the strongest with BMI than the others (WHR P<0.001; WSR P<0.01; and WC P<0.05) in women. Areas under the receiver operating characteristic (ROC) curves adjusted for age and cohort were slightly larger for diabetes for WSR 0.735 (0.748) in men (women) and WC 0.749 (women only) than BMI 0.725 (0.742) while for hypertension larger for BMI 0.760 (0.766) than WHR 0.748 (0.751), but their 95% CIs were all overlapped. DISCUSSION: WSR was stronger than BMI in association with diabetes, but these indicators were equally strongly associated with hypertension in Asians.