The short version
LADA (latent autoimmune diabetes in adults) is a form of diabetes where the immune system slowly destroys the insulin-producing cells in the pancreas, the same underlying process as Type 1 diabetes, but it happens gradually and usually starts after age 30. Because it develops slowly and shows up later in life, it’s frequently mistaken for Type 2 diabetes at first.
Some clinicians call it “Type 1.5 diabetes,” though that isn’t an official diagnostic category. It sits between the two better-known types: autoimmune like Type 1, slow-onset like Type 2.
How it differs from Type 1 and Type 2
- Type 1 diabetes usually appears in childhood or adolescence, progresses quickly (weeks to months), and requires insulin from diagnosis.
- Type 2 diabetes is primarily driven by insulin resistance, often appears alongside other metabolic factors, and can frequently be managed for years with lifestyle changes and non-insulin medication.
- LADA shares Type 1’s autoimmune cause but Type 2’s slow timeline. People with LADA often respond to oral medications for a period, sometimes a few months, sometimes several years, before their remaining insulin production drops enough that insulin becomes necessary.
Why it gets missed
Diagnostic criteria for LADA aren’t as standardized or widely tested for as Type 1 or Type 2. A doctor seeing an adult with high blood sugar will often diagnose Type 2 by default, since it’s statistically the most common cause at that age. LADA usually only comes to light when:
- Oral medications that should control Type 2 diabetes stop working faster than expected.
- The person is lean or doesn’t fit the typical Type 2 risk profile.
- Someone specifically requests antibody testing (see GAD65 antibodies explained).
What to ask your doctor
If your Type 2 diagnosis doesn’t quite add up, whether your medications stopped working, you don’t have the typical risk factors, or something just feels off, it’s reasonable to ask about antibody testing and a C-peptide test. Both are standard, inexpensive blood tests.
This page is educational, not medical advice. An endocrinologist can interpret your specific results.