Inside the pancreas, beta cells make the hormone insulin. With each meal, beta cells release insulin to help the body use or store the blood glucose it gets from food. In people with type 1 diabetes, the pancreas no longer makes insulin. The beta cells have been destroyed and they need insulin shots to use glucose from meals. People with type 2 diabetes make insulin, but their bodies don't respond well to it.

This article from the American Diabetes Association discusses insulin, medications and how they treat diabetes.