Diabetes mellitus refers to a group of diseases that affect how your body uses blood sugar (glucose). Glucose is vital to your health because it's an important source of energy for the cells that make up your muscles and tissues. It's also your brain's main source of fuel.

The underlying cause of diabetes varies by type. But, no matter what type of diabetes you have, it can lead to excess sugar in your blood. Too much sugar in your blood can lead to serious health problems.

Insulin is a hormone normally produced by the pancreas. Insulin helps your body convert food into energy. Without insulin, glucose (sugar) from food cannot enter cells, and builds up in the blood. Your body tissues become starved for energy.

How Type 2 Diabetes Occurs Copyright © Nucleus Medical Media, Inc.

Type 2 diabetes occurs because either one or both of the following conditions exist:

• Fat, muscle, or liver cells do not respond to the high levels of insulin (called insulin resistance)
• Beta cells in the pancreas do not make enough insulin relative to the demands of the body