Type 1 vs Type 2: Why It Matters
Reviewed by CDE Mehandi Sharma · Updated
Type 1 and Type 2 diabetes both produce high blood glucose. Almost everything else about them differs, including the treatment.
| Type 1 | Type 2 | |
|---|---|---|
| What goes wrong | Immune system destroys insulin-making cells | Body resists insulin; production falls slowly |
| Insulin production | Stops almost completely | Continues, often for years |
| Speed of onset | Days to weeks | Years |
| Insulin treatment | Essential from diagnosis, for life | Sometimes, usually later |
| Tablets | Do not replace insulin | Often the first treatment |
| Caused by diet or weight | No | Risk is raised by some lifestyle factors |
The practical stakes are high. Someone with Type 1 treated as though they had Type 2 — put on tablets and told to lose weight — is left without the insulin their body cannot make. That is how people end up seriously unwell.
It runs the other way too. Being wrongly labelled Type 1 can mean unnecessary lifelong injections.
Age is the usual reason for a wrong call, because Type 1 is assumed to be a childhood condition. It can start at any age. If an adult is diagnosed with Type 2 but is lean, deteriorated quickly, or has other autoimmune conditions, it is worth asking whether the type is confirmed.