Type two diabetes is basically insulin resistance as described by the previous answer. The cause, however, is not obesity, not lack of exercise, or poor health. If you have the genetics and eat a poor diet lacking in certain nutrients and high in useless calories (junk food), you will most likely become diabetic regardless of whether or not you're obese or inactive. As the cells become more and more resistant to the action of the body's insulin, glucose builds up in the blood... that's diabetes. Where most people get it wrong (especially nurses) is, a lot of normal weight, active people become type two diabetic. If this insulin resistance situation is allowed to go on too long, the body's pancreas keeps producing more and more insulin in an effort to get that built up glucose into the cells. This is the beginning of type two. Most people, in this condition, don't even know they have it yet. Eventually, the pancreas cannot keep up and "wears out", that's when the situation goes past the "borderline", or "pre-diabetes" stage into full blown where medical attention is usually indicated. If caught early enough while the pancreas can still produce adequate amounts of insulin, a type two diabetic can manage with healthy diet and exercise alone. I was dependent on pills up until I learned the little tidbit about potassium. Once I began consuming more fruits high in potassium, my blood sugar went down due to the potassium unblocking the insulin resistance and allowing what's left of my existing insulin production to get the job done. Since learning all this, trying different food and exercise combinations, I'm off the medication... hopefully, for good.