The aim of the study was to assess the effect of sitagliptin addition on the epicardial adipose tissue (EAT) thickness in subjects with type 2 diabetes mellitus inadequately controlled on metformin monotherapy. This was a 24-week interventional pilot study in 26 consecutive type 2 diabetic patients, 14 females and 12 males average age of 43.8 ± 9.0 years, with Hemoglobin A1c (HbA1c) ≥7 % on metformin monotherapy. Subjects who met the inclusion criteria were added on sitagliptin and started on sitagliptin/metformin combination at the dosage of 50 mg/1000 mg twice daily. EAT and visceral and total body fat were measured, respectively, with echocardiography and bioelectrical impedance analysis at baseline and after 24 weeks of sitagliptin/metformin treatment in each subject. HbA1c and plasma lipids were also measured. EAT decreased significantly from 9.98 ± 2.63 to 8.10 ± 2.11 mm, p = 0.001, accounting for a percentage of reduction (∆ %) of -15 % after 24 weeks of sitagliptin addition, whereas total body fat percentage, visceral fat, and body mass index (BMI), decreased by 8, 12, and 7 %, respectively (p = 0.001 for all). After 6 month, EAT ∆ % was significantly correlated with ∆ % of visceral fat (r = 0.456; p = 0.01), whereas no correlation with either BMI ∆ % (r = 0.292; p = 0.147) or HbA1c ∆ % was found. The addition of Sitagliptin produced a significant and rapid reduction of EAT, marker of organ-specific visceral fat, in overweight/obese individuals with type 2 diabetes inadequately controlled on metformin monotherapy. EAT as measured with ultrasound can serve as no invasive and accurate marker of visceral fat changes during pharmaceutical interventions targeting the fat.