A person with diabetes produces an insufficient amount of insulin, or cannot use insulin effectively enough to regulate blood glucose. Insulin is a hormone made by beta cells in the pancreas, and it helps move glucose from the bloodstream into cells for energy.
In type 1 diabetes, the immune system destroys the pancreatic beta cells that make insulin, so the body produces little or none. People with type 1 diabetes therefore need insulin replacement to survive. In type 2 diabetes, the body usually becomes resistant to insulin first; over time, the pancreas may fail to produce enough insulin to overcome that resistance.
This is why diabetes is often described as a problem of insulin production, insulin action, or both. The stored answer is the canonical response for a basic quiz, although “insulin resistance” is also an important part of type 2 diabetes.
Diabetes is not the same as temporarily having high blood sugar after a meal. Persistent blood-glucose elevation reflects problems with insulin regulation and requires medical assessment.