Background: Obesity is associated with type 2 diabetes mellitus (T2DM), but the obesity index most closely related to type 2 diabetes is still controversial. Therefore, the aim of this study was to compare the associations of five anthropometric indices (body mass index (BMI), body adiposity index (BAI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR)) with Type 2 diabetes mellitus (T2DM) among Chinese adults divided into four groups according to sex and age.Methods: A total of 4,007 adult participants (1,669 males and 2,338 females) were included. Odds ratios (OR) and 95% confidence intervals were used with binary logistic regression models to estimate the risk of T2DM for each obesity index. Furthermore, we compared the area under the ROC curve (AUC) of each obesity index for the criterion of hypertension under the influence of risk factors. Results: For the males, WC had the highest value of OR (3.211 and 1.452) and AUC (0.783 and 0.614) in both age groups. However, WHtR (OR=2.366, AUC=0.771) and BMI (OR=1.596, AUC=0.647) tended to be the best criteria for T2DM among females in the 18-59 and ≥60 years age groups, respectively.Conclusions: This study suggests that there is a positive association of obesity-related anthropometric indices with T2DM in different sex and age groups. For males, WC appears to be the best anthropometric index for predicting T2DM. For 18-59 and ≥60 age women, the best obesity indices related with T2DM are WHtR and BMI, respectively.