This study was conducted for the purpose of examining the effect of planned education given to persons with type 2 diabetes mellitus (DM) on their metabolic control. The method of the study was a randomly controlled clinical trial. A sample of 50 individuals participated, of which 25 were in the Experimental group (E), and 25 were in the Control group (C). The educational program consisted of three sessions between the educator and persons with diabetes. Before the education program, there was no statistically important significance between the metabolic control parameters of the E group and the C group. In the analysis of the difference between means of the E and C groups, after the third education program, statistically significant differences were found between fasting blood sugar, postparandial blood sugar, urine glucose, hemoglobin A1c, triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels. In the study, regular and repetitive education provided by the nurses had a positive effect on the metabolic values of persons with DM.