When you think of switching to a vegan lifestyle, you will usually find that most information is on what you eat and drink. There is, however, so much more that it entails.
The shoes that you wear as well as the clothes you wear play a part. Shoes need to be stitched together, and glue is one of the most common ways of doing this.
However, glue is not always free of animal products. Glue is traditionally made of collagen from animals. The only way to know is if the manufacturer has specifically mentioned the type of glue used. Otherwise, you have no way of knowing.
There is vegan-friendly shoe glue, and manufacturers have found that it is stronger and cheaper to use than animal-based glue.