The pancreas makes a substance called insulin that helps the body turn food into stored energy. In type 2 diabetes (adult-onset diabetes), the body still makes insulin but cannot use it normally. The result is high blood sugar (glucose) levels. Over time, high blood sugar levels can lead to many complications, including heart disease and stroke (cardiovascular disease). Some people have slightly high blood sugar levels for years before reaching diabetes levels, a condition called “impaired fasting glucose.” In 1997, blood sugar levels between 110 mg/dL and 125 mg/dL were defined as impaired fasting glucose. In 2003, the definition was changed to blood sugar levels between 100 mg/dL and 125 mg/dL because studies showed that even mildly high blood sugar levels were related to health problems. People who do not have cardiovascular disease are at higher risk for developing it if they have impaired fasting glucose than if they have normal blood sugar levels. Whether impaired fasting glucose increases the risk for new cardiovascular events in people who already have cardiovascular disease is not known.