Also an umbrella term, "Syndrome X" was coined in 1988 by Stanford University Professor of Medicine Gerald Reaven to describe the cardiovascular effects usually observed when insulin levels are persistently elevated, as they are in many diabetics. Syndrome X traits include high blood pressure, abnormalities in the amount and properties of certain blood fats, and abnormalities in blood clotting factors. Together, these are believed to contribute significantly to the unusually high rate of death from heart disease (roughly 75 percent) among diabetics.
Insulin is a powerful hormone that can constrict blood vessels and interfere with several processes in the body. But its primary job is to shepherd incoming nutrients. Released by the pancreas when we eat, insulin guides the amino acids from protein to our muscle cells, and takes fatty acids to the fat cells.
Carbohydrates are first broken down into "blood sugar" glucose, which the body uses for energy. Insulin makes sure there's never too much of that caustic fuel lingering in the bloodstream by storing excess glucose in the liver and fat cells, and shuttling just what's needed for energy at the moment to the various cells of the body. Insulin even unlocks a sort of door on each cell, allowing glucose to enter.
But when cells no longer answer the door to insulin, the body is said to have become "insulin resistant." No one is sure what first triggers the change. Obesity is one factor observed to foster insulin resistance, but heredity also plays a role, and even a thin person can become insulin resistant.
When glucose is thus locked out of resistant cells, it has nowhere to go and starts building up in the bloodstream. The pancreas releases yet more insulin to try to compensate, and for a while, that works to force glucose through the cell doors.