Non-surgical periodontal treatment (NSPT) is the primary approach to managing periodontal infections. Our study aimed to evaluate and compare HbA1c levels between non-diabetic subjects with chronic periodontitis and subjects with a healthy periodontium. In addition, this study evaluated the effect of NSPT on blood glucose regulation in non-diabetic patients with chronic periodontitis. This clinical trial divided participants into two groups: an intervention group consisting of 20 non-diabetic subjects with a diagnosis of chronic periodontitis and a control group consisting of 20 non-diabetic individuals with healthy periodontal tissues. Periodontal clinical parameters, including gingival index (GI), probing pocket depth (PPD), clinical attachment loss (CAL), and HbA1c levels, were recorded. The intervention group underwent NSPT, and after three months, their periodontal parameters and HbA1c levels were reassessed and compared with baseline values. Before treatment, the HbA1c levels in the intervention group were significantly higher than those in the control group (P < 0.001). In the intervention group, a significant decrease in HbA1c levels was observed after treatment (P < 0.001), whereas the control group showed no significant change (P > 0.001). These findings suggest that chronic periodontitis may affect blood sugar levels even in non-diabetic individuals. Furthermore, NSPT not only improves periodontal health but also helps to reduce HbA1c levels.