Despite what you may see on store shelves, there is no official "diabetes multivitamin." At this point, the assumption is that what's good for the general population is also good for you. Some brands provide higher-than-recommended levels of other nutrients, which is usually fine as long as the nutrient is safe at higher levels.
Before buying a multivitamin, check the supplement facts panel for the serving size. You should have to take only one pill to get the nutrients listed below; put back those requiring two or more tablets. They're often loaded with unnecessary and unproven ingredients. Unlike drugs, supplements are not well regulated, so there's no guarantee that you're getting a safe and effective product. Generally, the big companies are a good bet. One measure of comfort is if the multivitamin is marked "USP Verified" or has the "USP" symbol. This means an independent organization called the U.S. Pharmacopeia has inspected the plant where the supplements are made and tested the products for purity, potency, and the ability to break down in the digestive tract (otherwise they won't be absorbed into your body). However, some companies with good products opt out of the USP testing.