Causes of high glucose levels can be from a few things. For instance, in a lot of the foods you may eat in your normal diet could have an impact. Foods with a lot of carbs are first on the list. Not making sure that you get enough exercise is another thing that can make your levels a bit higher. Now no one is saying you need to be a gym junkie, but working out on a regular basis and eating healthy are two good ways to keep your glucose levels at a norm.