Overview To investigate whether serum ischemia-modified albumin or C-reactive protein is reliable for predicting type 2 diabetic patients with ketosis. Approach One hundred and four diabetic patients, 48 with diabetic ketosis, and 33 controls were enrolled in the study. Serum ischemia-modified albumin and C-reactive protein were measured and evaluated for their ability to distinguish diabetic ketosis. Results Compared to the controls, the ischemia-modified albumin and C-reactive protein levels were higher in patients with diabetic ketosis and type 2 diabetes at the baseline. The levels of ischemia-modified albumin were higher in patients with type 2 diabetes than in the controls. C-reactive protein and ischemia-modified albumin levels were reduced after insulin treatment. The level of ischemia-modified albumin was an independent risk marker for diabetic ketosis ( OR = 1.085, P = 0.008, 95% CI: 1.022–1.152). Receiver operating characteristic curves revealed that the areas under the curve were 0.917 for the modified albumin and 0.357 for C-reactive protein. Conclusion This study indicates that ischemia-modified albumin was significantly associated with diabetic ketosis and was more sensitive than C-reactive protein in reflecting diabetic ketosis.