Insulin resistance and insufficient insulin production
Insulin resistance in type 2 diabetes means the signal insulin gives to a cell is weakened. This results in less glucose uptake by muscle and fat cells and a reduction in insulin mediated activities inside cells. Compounding this problem of resistance, there is additional defect in insulin production and secretion by the insulin producing cells, the beta cells in the pancreas.
As a group, everyone with with type 2 diabetes has both insulin resistance and an inability to overcome the resistance by secreting more insulin. But any given individual with type 2 may have more resistance than insulin insufficiency or the opposite, more insulin insufficiency than resistance. And the problems may be mild or severe. It is believed that the wide range of clinical presentation is because there are many, many genetic causes – and combinations of genetic causes – of type 2 diabetes. At present there is no single genetic test for type 2 diabetes. The diagnosis is made on the basis of the individual having clinical features consistent with type 2 diabetes, and by excluding other forms of diabetes.