Type 1 and type 2 diabetesSpec D3.3.4
In short
Diabetes is a condition in which blood glucose is not kept within its normal limits. In type 1 diabetes the immune system destroys the β cells, so little or no insulin is secreted. In type 2 diabetes target cells become resistant to insulin. Type 1 is treated with insulin; type 2 is largely prevented and managed by diet and exercise.
| Type 1 | Type 2 | |
|---|---|---|
| Physiological change | Autoimmune destruction of the β cells, so little or no insulin is secreted | Target cells become less responsive to insulin (insulin resistance), e.g. fewer working insulin receptors or glucose transporters; insulin is still produced, though output may fall later |
| Usual onset | Often in childhood or adolescence | Usually in adults, increasingly in younger people |
| Risk factors | Genetic predisposition; possibly environmental triggers such as viral infection | Obesity, physical inactivity, diets high in sugar and fat, increasing age, family history (genetic factors) and ethnicity |
| Prevention | No known method | Healthy diet, regular exercise and keeping a healthy body mass |
| Treatment | Regular insulin injections or an insulin pump, matched to blood glucose monitoring, meals and activity | Diet low in sugars and refined carbohydrates, exercise, weight loss; drugs that improve insulin sensitivity; insulin in some cases |
In both types, blood glucose rises after meals and stays high (hyperglycaemia). Glucose appears in the urine and, over many years, high glucose damages blood vessels, nerves, kidneys and the retina.
For 'distinguish' questions, state the difference in physiology directly: type 1, no insulin is produced; type 2, insulin is produced but target cells do not respond to it.
Written and checked against the IB Biology HL specification · Updated October 2026