Foods like antioxidant-rich blueberries, nuts, and fish with omega-3 fatty acids are great for your ticker not only because of the heart-healthy nutrients the contain, but also because they are low on a scale known as the glycemic index. The glycemic index ranks foods according to how much they impact the level of sugar, or glucose, in the bloodstream.

You get glucose from the foods you eat, either from foods containing sugar itself, or from eating carbohydrates, which the body transforms into glucose. To do this, the body secretes insulin, which is a hormone produced in the pancreas.

Over time, eating too much sugar can cause your pancreas to become less effective at releasing insulin, which, in turn, can result in diabetes. By eating foods that are low on the glycemic index, you keep your glucose levels normal and avoid the unhealthy insulin spikes that lead to a less effective pancreas and insulin deficiency.

The glycemic index is a measure of the rise in blood sugar that a food causes “indexed” to 100.

Foods with a glycemic index of less than 55 are considered low; these include beans, most fruits and vegetables, and whole grains. A medium glycemic index score is between 55 and 70; foods ranked at this level include whole wheat, sweet potatoes, and baked potatoes. High glycemia is above 70; foods rated high include refined grains such as white bread and white rice, as well as corn flakes.