Background Type 2 diabetes is increasingly diagnosed at a younger age worldwide and in China. Limited data are available regarding the association between age at diabetes diagnosis and risks of albuminuria. This study sought to examine the independent effect of age at diagnosis of type 2 diabetes on the risk of albuminuria. Methods We used data from a nationwide multicenter study with 207 961 participants in mainland China. Age, sex, and study site were matched for 31 366 screen-detected type 2 diabetes cases and 31 366 normal controls. Age, sex, study site, and diabetes duration were matched for 7490 self-reported type 2 diabetes cases and 7490 normal controls. Risks of having albuminuria in matched type 2 diabetes vs controls were examined using multivariable logistic regression analysis in strata of age at diabetes diagnosis. Results Although the absolute rate of albuminuria is higher in older adults, the odds ratio of albuminuria in type 2 diabetes vs matched controls decreased with increasing age at diagnosis. For participants with diabetes diagnosed at an age of <50, 50 to 59, 60 to 69, or >= 70 years, the multivariable adjusted risk of albuminuria increased by 81%, 60%, 45%, and 33% for screen-detected diabetes, and 135%, 121%, 90%, and 58% for self-reported diabetes compared with their normal controls, respectively. Conclusions A younger age at diagnosis of type 2 diabetes is associated with a more significantly elevated risk of albuminuria than an older age at diagnosis in Chinese adults.