Colorado requires a SR-22, a rider added to an insurance policy, be obtained when you are convicted of a DUI. The sr-22 form itself is not an insurance policy, but instead is a guarantee by the insurance company that you will keep insurance in effect for a certain period.
If are required to have the SR22 and do not keep the SR22 current, the insurance company will notify the CO Motor Vehicle Division (MVD) at which point your license will be suspended.
How long you are required to have the SR-22 appears to typically be 3 years. Colorado legislator also notes that under some circumstance, such as those with an alcohol related driving offense, it could be for a different period, such as only as long as the insured's license has been restraint.
So it would seem that the SR-22 would have to be maintained for either 3 years or for a period equal to the duration of your license revocation. To find out for certain you can contact the Colorado Motor Vehicle Division.