Vaccination in diabetics is important to prevent cardiac complications that happen in type -2 diabetes mellitus after COVID-19 infections. Measurement of Reactive Oxygen Species (ROS) as indicators of oxidative stress in T2DM patients. and measuring variable of cardiac function test (Troponin-I, creatine kinase CK-MB) after the second dose of Pfizer vaccination. ROS (Reactive oxygen species) and cardiac function tests (Troponin-I, CK-MB) were determined by using an ELISA kit. The results revealed a higher level of ROS in both group of diabetic in comparison to controls elevated in diabetic (slightly higher in diabetics non vaccinated than vaccinated) I compare with healthy controls lower, while cardiac function tests including Troponin-I higher in diabetics (vaccinated higher than non-vaccinated) in compare with healthy control.CK-MB higher in diabetics and healthy vaccinated in compare with diabetics non vaccinated. ROS not changed after Pfizer vaccination. Vaccinated type 2 diabetes show marginal elevated in Cardiac function test and ALL Cardiac function test mean with normal range (diabetics show higher level of Troponin-I in compare with healthy control) while CK-MB higher in diabetics vaccinated and healthy control in compare with diabetics non vaccinated.