Diabetes mellitus (diabetes) is a complex, progressive and chronic disease caused by insufficient production of insulin and/or resistance to insulin. Insulin is a hormone produced in the pancreas. It promotes the uptake of glucose from the blood stream into the cells, where it is then metabolised as an energy source. When there is insufficient production of insulin and/or the body resists insulin, blood glucose levels become too high and type 2 diabetes can occur. There are multiple types of diabetes. Type 2 diabetes is a largely preventable and reversible form that develops through age and weight gain in genetically susceptible people, when both the cells become resistant to insulin and the pancreas fails to produce enough insulin. As discussed above, insufficient insulin and/or a lack of response to insulin by the body's cells, leads to high blood glucose levels, which causes damage to blood vessels over time. Early symptoms of type 2 diabetes can easily go unnoticed and typically include fatigue, excessive thirst, frequent urination, frequent infections, hunger, and blurred vision. Diagnosis can be made through a blood test which measures the average glycated haemoglobin (HbAIC) content of the blood over a two to three-month period. If type 2 diabetes is not managed, long-term damage of blood vessels can lead to more serious complications such as heart and blood vessel disease, nerve damage (which can eventually lead to amputation), kidney damage, eye damage, slow healing, hearing impairment, skin conditions, sleep apnea and Alzheimer's disease". Maintaining blood glucose levels within the normal range can help to prevent these complications from developing.