Insulin is a naturally occurring hormone made by the pancreas that helps our body use or store the glucose (sugar) it gets from food. For people with diabetes, either the pancreas does not make enough insulin to meet the body's requirements, or the body cannot properly use the insulin that is made.
The yellow color in normal urine comes from a substance known as urochrome. Urochrome is also known as urobilin and is the result of hemoglobin breakdown. Hemoglobin is the protein in red blood cells that enables oxygen to be taken around the body.
Most multivitamins will cause your urine to turn high lighter yellow. Not just B vitamins but an increase in things like carrots and squash or anything with beta-caratin in it can also cause the coloring. (I apologize if I spelled anything wrong.). As most everyone on here has said, it's nothing to worry about.