Diabetes mellitus is associated with an increased risk of cardiac complications, this study aimed to investigate effect of sitagliptin (SITA) alone or combined with γ-irradiation on diabetes-associated cardiac injury. Rats were treated with SITA (100 mg/kg/day; p.o.) for 2 weeks followed by single dose whole body γ-irradiation (3 Gy). Solitary administration of SITA or combined treatment with γ-irradiation succeeded to ameliorate the increase in serum levels of glucose, total cholesterol (TC), triglycerides (TG), creatine kinase-MB (CK-MB) and malondialdyhyde (MDA) coupled by increased insulin and reduced glutathione (GSH) levels. Their cardioprotective potential was confirmed through attenuating the apoptotic signaling by mitigating Bcl-2-associated X protein (Bax), caspase-3 and apoptosis inducing factor (AIF) expression, while augmenting the anti-apoptotic factors, B cell lymphoma-2 (Bcl-2) and heat shock protein 70 (HSP-70) in left ventricular tissue homogenates. These findings were supported histopathologically. In conclusion, treatment with SITA alone or combined with γ-irradiation may prove beneficial in diabetes-accompanied cardiac insult. This could be due to the crosstalk between the antioxidant, anti-apoptotic and restoration of body’s defense capacities.