Type one is a condition where the pancreas no longer secretes enough insulin to keep blood sugars normal. These people always need insulin and will die sooner or later if they don't get it.
Type two is a conditon of insulin resistance and to start with the pancreas of these people secretes more insulin than previously. Eventually the pancreatic beta cells get exhausted and die off and then these people need insulin injections. Sometimes people say that they then become type one but it is more correct to say that they are type two diabetics who are insulin dependent.
