Materials and Methods: In this randomized clinical trial study, 48 patients with type 2 diabetes mellitus participated in the GVS, sham GVS, and the no-treatment group as the control group (mean age of 50.79 ± 6.65 years). In the GVS group, each subject received electrical stimulation three times a week via two electrodes on mastoid processes throughout the 12-week study period. The current for sham stimuli was reduced to zero after about 10 seconds. The blood samples were used to monitor the blood sugar level and HbA1C changes. Body mass index (BMI) changes were assessed as well. The one-way ANOVA technique and Tukey"s test were applied to compare the values between the groups. A paired-samples t-test was applied to individually compare the baseline and 12-weeks values of BMI, fasting blood sugar, and hemoglobin A1C in the groups.

Results: The comparison of the results in the three groups showed a statistically significant reduction in the blood sugar level and BMI in the GVS group (P < 0.05).

Conclusions: The findings of the current study demonstrated that in patients with diabetes, GVS, along with receiving medical treatment, led to a further reduction in the blood sugar level and BMI, and thus this method can be used to treat patients with treatment-resistant diabetes and lower pharmacotherapy.