How do type 1 diabetes and type 2 diabetes differ in their effects on insulin?

Type 1 and type 2 diabetes mellitus differ fundamentally in how they affect insulin production and utilization:

• Type 1 Diabetes: This is an autoimmune condition characterized by the destruction of the insulin-producing beta cells within the islets of Langerhans in the pancreas. Because these cells are destroyed, the body suffers from a severe lack of insulin, necessitating external insulin administration to regulate blood glucose levels.312

• Type 2 Diabetes: This form is primarily defined by insulin resistance, where the body's cells—particularly muscle and adipose tissue—fail to respond effectively to insulin. While patients may initially have higher-than-normal serum insulin concentrations as a compensatory response, many eventually experience insulin deficiency when the pancreas can no longer produce enough insulin to overcome this resistance.451

In both cases, the underlying dysfunction leads to hyperglycemia, as the body loses its ability to properly trigger cells to take up and metabolize glucose for energy.4