A DUI stays permanently on your driving record in California... there is no "diversion program" that relates to a DUI. Perhaps you are doing a diversion program in order to avoid being convicted of a drug offense. The completion of such a drug diversion program will result the drug offense being dismissed, but not the DUI.
There is no diversion for a DUI in CA. You likely are referring to the first offender program which is usually a probation term and is required for you to get a full driving privilege back from the DMV.
The conviction stays on your record forever and is priorable for 10 years.
You may be able to expunge/dismiss your case when you are off probation.
http://www.stankolaw.com