Abstract: Background: Diabetic patients are at increased risk of cardiac arrhythmias and sudden death. Interplay of several concomitant factors in diabetic patients may facilitate the occurrence of arrhythmia. Inflammation has been shown to play a direct role in the initiation, maintenance and recurrence of atrial fibrillation (AF) in all patients. However, few studies have evaluated the association between diabetes mellitus and cardiac rhythm disorders. We tried to detect the association between inflammation and cardiac electrical instability. Methods: Ninety diabetic patients with structurally normal hearts were enrolled in the study and followed up for one year. In every three-months visit, we assessed cardiac rhythm, P wave dispersion, hs-CRP level and random blood sugar.Results: One third of the original cohort succeeded to complete the follow up schedule. Arrhythmia developed at a time during the follow up period in about one third of patients. There was positive correlation between hs-CRP and P wave dispersion and rhythm disturbances (r 0.4-0.8 and p < 0.05). Conclusion: We concluded that diabetic patients are in high risk for cardiac arrhythmias. P wave dispersion and hs-CRP are interrelated and they proved to be strong predictors for cardiac electrical instability and hence arrhythmia production.