How much will it cost to buy health coverage on Minnesota’s new insurance exchange? We won’t know until it’s up and running.

Insurance carriers that want to be part of the exchange have submitted their rate proposals to state regulators. But MPR reports that -- unlike several other states -- Minnesota will keep that information confidential until the MNsure website goes live in October.

State Sen. Joe Atkins says the law that created the insurance exchange contains that provision because state officials reasoned it would improve competition among insurers. "If they can see each other's rates, then what they tend to do is just under-bid one another by a nickel or two, and it doesn't drive down prices," Atkins told MPR.

Minnesota's approach is in contrast to other states that are now releasing rate information.

The Fiscal Times reported last week that early indications show the effect of the exchanges on insurance premiums are a mixed bag. In five states where health insurance is already highly regulated, average premiums will be the same or lower. In states with more lenient regulations, rates are headed upward.

Ohio announced last week it foresees an average rate increase of 88 percent. In California residents will pay different rates for the same insurance plan depending on where in the state they live.

In Minnesota state officials expect about 1.3 million residents to buy health coverage through the exchange, including 300,000 who currently lack insurance. The state has produced a video introduction to MNsure, which rolls out on October 1.