Aims/hypothesis: This prospective association study aimed to compare the relationship between each of four obesity indices and mortality risk in people with type 2 diabetes. Methods: The associations of BMI, waist circumference, WHR and A Body Shape Index (ABSI) with all-cause mortality were analysed in 1282 participants of the Fremantle Diabetes Study, followed for up to 20 years after baseline assessment. Models were adjusted for age and other confounders; assessments as continuous measures and by quintile were carried out for men and women separately. Sensitivity analyses were conducted to minimise reverse causality. Results: When indices were assessed as continuous variables, there were significant bivariate associations with mortality for: ABSI, which was greater in both men and women who died (p < 0.001); WHR, which was greater in women only (p = 0.033); and BMI, which was lower in women only (p < 0.001). When assessed by quintile, there were significant bivariate associations with mortality for ABSI in men and women (p < 0.001) and BMI in women only (p = 0.002). In Cox models of time to death, adjusted for age, diabetes duration, ethnicity and smoking, ABSI quintiles showed a linear trend for both men (p = 0.003) and women (p = 0.035). Men in the fifth ABSI quintile had an increased mortality risk compared with those in the first quintile (HR [95% CI]: 1.74 [1.24, 2.44]) and women in the fifth ABSI quintile had an increased mortality risk that approached statistical significance (1.42 [0.97, 2.08], p = 0.08). Men in the fifth WHR quintile had an increased mortality risk (1.47 [1.05, 2.06]). There was no association between mortality and BMI or waist circumference in either sex. Conclusions/interpretation: ABSI was the obesity index most strongly associated with all-cause mortality in Australians with type 2 diabetes. There was no evidence for an obesity paradox with any of the assessed indices. ABSI may be a better index of central obesity than waist circumference, BMI or WHR when assessing mortality risk in type 2 diabetes.