Exercise is vital for diabetics to improve their blood glucose level. However, the quantitative relationship between exercise modes (including types, intensity, time, etc.) and the blood glucose is still not clear. In order to answer these questions, this paper established a blood glucose metabolic model based on ordinary differential equation method. Furthermore, a silico method was adopted to study the effects of different aerobic exercise intensities (light, moderate and vigorous) on blood glucose and optimal strategies of insulin infusion for type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). Additionally, the universality of proposed model and insulin infusion strategies was verified based on 1 000 virtual diabetes patients’ simulation. The experimental results showed that: (1) Vigorous-intensity aerobic exercise may result in hypoglycemia (< 3.89 mmol/L), which was so harmful to health that diabetics should avoid. Compared with moderate-intensity exercise, the light-intensity aerobic exercise intuitively lowered blood glucose slowly and caused a relative long high-blood-glucose (> 6.11 mmol/L) period, however, its overall blood glucose risk index (BGRI) was lower. (2) Insulin dosage of the optimized strategies decreased by 50% and 84% for T1DM and T2DM when they did moderate intensity exercise. As for light intensity exercise, the dosage of insulin was almost the same as they didn’t do exercise, but BGRI decreased significantly. (3) The simulations of 1 000 virtual diabetic patients manifested that the proposed model and the insulin infusion strategies had good universality. The results of this study can not only help to improve the quantitative understanding about the effects of aerobic exercise on blood glucose of diabetic patients, but also contribute to the regulation and management of blood glucose in exercise mode.