Most insurance companies check your credit history as a matter of course. A formula is applied to your credit score to help determine what is known as an insurance score, and that is used in setting your premiums by assessing the risk you pose of such things as nonpayment of your policy and other financial indicators.
You may be able to shop around and find an insurance company that does not use your credit score at all, but it may be easier to simply look at the weight such a score is given by different insurers. If you have a good driving hisotry but a low credit score, you may be able to offset the costs of the credit assessment with discounts attributed to your actual driving history.
Credit scoring indicates more than your credit risk, including providing insurers and lenders with a gauge of how well and promptly you pay your bills and whether or not you are a stable risk to insure. It is used with over a dozen other factors such as where you live and your level of education to place you in the correct risk group. Even if you have bad credit, insurance will still be available to you, but it may force you into a slightly higher risk group.
To help you understand how the credit score is important, consider that insurance companies do not base rates on an individual, but rather on the behavior of demographically similar group of people. When all of the factors for the group are used together, a dependable estimate of the general behavior of the group emerges. Your credit score, as one of those factors, is simply one piece of a much larger puzzle based on real-world situations and statistics.