Think of insulin as a delivery system.

Insulin is a hormone that is made in your body naturally. The pancreas, an organ near your stomach, makes insulin each time there is a rise in blood sugar levels.  Blood sugar levels usually rise after a person eats a meal. That’s when the body takes the food you ate and turns it into sugar, or glucose. The insulin in your body works like a delivery system. It delivers sugar from your blood into the cells of your body. 

When you have diabetes, your body cannot make enough insulin or it has trouble using the insulin it makes. When you don’t have enough insulin, there’s nothing to take the sugar from your blood to the cells. That means there is too much sugar in your blood. This extra sugar is what makes people feel the symptoms of diabetes (ie, feeling tired, always thirsty).