Does getting a DUI in another state affect your auto insurance?

Most likely, yes. States have reciprocity laws and procedures which allow them to share pertinent information on drivers in other states. Your carrier might also have other resources to check on this sort of thing.

Also, by not reporting a DUI to your carrier, you are essentially misrepresenting yourself to them. The premium you pay is clearly not based on you having received a DUI, which places you -- rightly so-- in a much higher risk category. You could have possible coverage issues if you have a loss and expect your carrier to pay out on it, not to mention the fact that your carrier could drop you altogether. This would look terrible on your record when you, say, go to get insurance from a different carrier.

Your best bet is to simply own up to the DUI with your current carrier. At your renewal, you'll see a huge premium increase or, unfortunately, your carrier will choose to drop you because you're viewed as an unacceptable risk. If the latter occurs, you'll have to shop around for another carrier, but high-risk carriers do exist. They're very, very pricey, but you definitely do not want to risk driving without insurance.