Background: Blood pressure (BP) readings taken at a doctor's office or clinic have historically served as the foundation for the diagnosis, treatment, and estimation of mortality risk for patients with hypertension. Objective: The present study aimed to measure the relative predictive value of office-based BP versus ambulatory BP for cardiovascular complications in diabetes patients. Patients and methods: This cohort study included 48 adult diabetic patients from Cardiology Department, Zagazig University. The examined cases had at least two consecutive BP clinic measures with a validated automatic oscillometric instrument or the conventional approach using a sphygmomanometer. Results: Office systolic blood pressure ranged from 107 to 138 mmHg with a mean of 126.88 mmHg. Office diastolic blood pressure ranged from 53 to 79 mmHg with a mean of 71.98 mmHg. Mean 24-hour systolic blood pressure ranged from 105 to 147 mmHg with a mean of 122.69 mmHg. Mean 24-hour diastolic blood pressure ranged from 51 to 90 mmHg with a mean of 70.5 mmHg. There was statistically significant positive correlation between office SBP and both daytime and night ambulatory systolic blood pressure. There was statistically significant positive correlation between office DBP and both daytime and night ambulatory diastolic blood pressure. There was statistically significant positive correlation between office MBP and both ambulatory mean 24-hour systolic and diastolic blood pressure Conclusion: Ambulatory blood pressure monitoring (ABPM) is linked to the development of cardiovascular problems from diabetes and diabetic retinopathy at a mean ambulatory BP level of less than 122.5/70.5 mmHg.