Diabetes Mellitus (DM) type 2 is a degenerative disease which characterized by blood glucose higher than the normal level and insulin metabolism disorder. The low level of glycemic index in food can decrease blood glucose and help DM patient to maintain their blood glucose. This research was aimed to develop sweet purple potatoes and red bean to make ready to eat breakfast cereal and its effect to glycemic response. From this research, the formulation that was chosen was flakes with ratio of purple sweet potato and red bean 90:10 due to moisture content 3.61%, ash content 4.86%, fat content 0.51%, protein content 5.11%, carbohydrate content 77.06%, dietary fiber content 9.88%, and amylose content 36.43%. The other parameters are physical characteristics such as hardness (416.36 gram), the color of this flakes is red purple, and its water absorption 106.65%. The selective formulation was evaluated for its effect on glycemic response. The test conducted by testing blood sugar of 11 subjects (5 male and 6 female) aged 21 to 22 years old. The selective formulation has a glycemic response curve resembled the curve of low glycemic index food if compare to control. IUAC value of flakes also lower than control, it means that flakes has a lower glycemic index than control