Post prandial blood sugar is a measurement of the concentration of glucose in your bloodstream up to four hours after eating a meal. When you eat, your body converts carbohydrates in foods into simple sugars such as glucose and fructose, which are then absorbed into your bloodstream. Along with fat, glucose is the body’s primary fuel source. Every cell in your body is powered by this source of energy. In addition to ingesting glucose from food, your body can produce it through a process known as gluconeogenesis.