Here is a link to a great article on how diet soda increases the rate of diabetes. I urge you to begin questioning the impact that your choices have on your health. There has been a concept through our culture that we can create an alternative to the natural process and this will some how substitute the adverse impact that our decisions can create. Diet soda is one of the worst substances that you can put into your body. It is better to always stick with the original substance (real sugar) because your body knows what to do with it. When you start introducing artificial sweeteners into your body (sorbitol, aspartame, etc..), your physiology does not know how to process and eliminate it. Thus it will store the toxicity. This toxicity will store in the nervous system and create a wide range of negative function. This will eventually impact your insulin response leading to an increase in blood sugar. Here is your tip for the day- stay far away from food products such as artificial sweeteners and high fructose corn syrup.
http://www.medscape.com/viewarticle/779290?src=wnl_edit_medn_wir&uac=142857PG&spon=34