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.
Dark yellow colored urine does not always indicate UTI as there are nearly 40 other reasons due to which urine could turn dark yellow in color. Extreme dehydration. However, if you feel you are drinking tons of water but still suffering from dark yellow urine, it is time to go in for urinanalysis.