Diabetes mellitus is a group of metabolic diseases in which the person has high blood glucose (blood sugar) level either due to inadequate insulin production or because the body's cells do not respond properly to insulin or both. It describes a metabolic disorder of multiple etiology characterized by chronic hyperglycemia with disturbances of carbohydrate, fat (dyslipidaemia) and protein metabolism resulting from defects in insulin secretion, insulin action, or both.

The main symptoms are: - Polyuria (frequent urination), Polydipsia (increased thirst), Polyphagia (increased hunger) Blood glucose is the main type of sugar found in your blood and your main source of energy. Glucose comes from the food you eat and is also made in your liver and muscles. Your blood carries glucose to all of your body’s cells to use for energy.

Your pancreas—an organ, located between your stomach and spine, that helps with digestion—releases a hormone it makes, called insulin, into your blood. Insulin helps your blood carry glucose to all your body’s cells. Sometimes your body doesn’t make enough insulin or the insulin doesn’t work the way it should. Glucose then stays in your blood and doesn’t reach your cells. Your blood glucose levels get too high and can cause diabetes or prediabetes. Over time, having too much glucose in your blood can cause health problems.

Type 2 diabetes is a progressive disease, meaning that the body’s ability to regulate blood sugar gets worse over time, despite careful management. Over time, the body’s cells become increasingly less responsive to insulin (increased insulin resistance) and beta cells in the pancreas produce less and less insulin (called beta-cell burnout). In fact, when people are diagnosed with type 2 diabetes, they usually have already lost up to 50% or more of their beta cell function.

As type 2 diabetes progresses, people typically need to add one or more different types of medications. The good news is that there are many more choices available for treatments, and a number of these medications don’t cause as much hypoglycemia, hunger and/or weight gain. Diligent management early on can help preserve remaining beta cell function and sometimes slow progression of the disease, although the need to use more and different types of medications does not mean that you have failed.