Obesity is a risk factor for diabetes. A major cause of diabetes is insulin resistance. Scientists are still searching for the causes of insulin resistance, but they have identified two possibilities. The first could be a defect in insulin receptors on cells. Like an appliance that needs to be plugged into an electrical outlet, insulin has to bind to a receptor to function.
Several things can go wrong with receptors.
There may not be enough receptors for insulin to bind to, or a defect in the receptors may prevent insulin from binding. A second possible cause involves the process that occurs after insulin plugs into the receptor. Insulin may bind to the receptor, but the cells don't read the signal to metabolize the glucose. Scientists are studying cells to see why this might happen.