Prediabetes occurs when the body does not respond properly to the hormone insulin and therefore cannot keep blood glucose (sugar) levels within a normal range. Blood sugar is higher than normal, but not high enough to be diabetes.

The food you eat turns into blood glucose, or sugar. The bloodstream transports glucose to all the cells in your body to be used for energy. Normally, the pancreas produces insulin, which allows the sugar in the blood to enter the body's cells. When your body's tissues are not responding properly to insulin, it becomes difficult for cells to get glucose from the blood for energy. This is called insulin resistance. When this happens, the cells cannot use the glucose, which then remains in the blood.

The buildup of sugar in the blood causes prediabetes. Over time, if not treated, the condition may get worse and lead to type 2 diabetes and other serious complications such as heart and large blood vessel disease, stroke, impaired vision, and nerve and kidney disease.