Type 2 diabetes is most often caused by cells becoming less sensitive to the hormone insulin. This phenomenon is called insulin resistance. Insulin normally signals cells to grab up and use sugar (glucose) from the bloodstream, so if cells are not getting the message, glucose stays in the blood. But what makes cells ignore this critical message? While the exact causes remain unknown, it appears that having high levels of insulin in the blood for a prolonged period can alter the receiving mechanisms that many cells have for insulin (called insulin receptors) making them less able to respond to the message.

So what makes insulin levels high in the first place? Unfortunately, scientists do not know exactly why this happens, but one thing is clear: obesity is a major factor. Several other risk factors are known including other preventable risk factors, like high blood pressure and some that are not preventable, like family history.

Type 2 diabetes can also occur when the pancreas produces only low levels of insulin. In this case, there is not enough insulin to signal body cells to take up sugar and the result is the same as insulin resistance: high blood sugar and starving cells.