Right now, the jury is still out on whether or not Beta cells can regenerate once they've been burned out. The evidence right now is on the side of "they don't". Does that mean you are doomed once you're diagnosed with diabetes? I don't think so at all! There are many things that you can do to get better control and keep it such as losing weight (to increase insulin sensitivity and put less strain on your existing beta cells), cutting carbs (again, to put less stress on your pancreas) and excercising (increases that insulin sensitivity again).
I've been low carbing for over 2 years and maintaining near-normal blood sugars around the clock. Am I cured? No way! One high carb meal shows me that on my blood sugar meeter within 2 hours or less.
Could someone with better pancreas function who is still diabetic get away with eating that same high carb meal? Maybe, but given that the high carb meal is causing the pancreas to work harder again, are they really getting away with anything? I fell into that trap several years ago, thinking that since my blood sugars were okay with the way I was eating (higher carb), I was okay and it bit me on the butt big time.
I don't honestly believe that there is any such thing as being "cured" of diabetes. There's only better or poorer control IMHO and we all have control over that if we wish to exercise it.