Background: An assessment scale, namely, the DMIST (deep, moisture, infection/inflammation, size, tissue type of wound bed, type of wound edge and tunnelling/undermining), was designed to identify the healing time of chronic ulcers. An evaluation was then conducted to test the predictive validity of DMIST. This study aimed to evaluate whether the total scores from the DMIST scale could predict healing time of diabetic ulcer. Method: A prospective study cohort was obtained from the Kitamura Wound Clinic in Pontianak, Indonesia. A total of 33 patients with diabetic ulcer were recruited to participate in the study. Collected data included DMIST score, demographic information, Wagner wound classification, neuropathic status, ankle brachial index, HbA1c level and wound images. Using the DMIST scale, trained data collectors scored patients every 7 days until ulcers were healed or patients were discharged. Results: A cutoff score of 9 was valid as a predictor of non-healing after 12 weeks. The DMIST scale was found to have high sensitivity (90%) and specificity (96%). The area under the receiver operating characteristic curve was 0.98 (95% confidence interval, 0.856 to 1.000). Conclusion: The DMIST scale was found to be a valid assessment scale to identify wound healing time in a period of 12 weeks in patients with diabetic ulcer.