LADA: The Slow-Onset Autoimmune Diabetes Often Mistaken for Type 2

Some adults diagnosed with type 2 diabetes turn out to have something else: an autoimmune form of diabetes that starts slowly enough to look like type 2 at first. It is called latent autoimmune diabetes in adults, or LADA, and getting the label right changes how it should be treated.

This article is general education. Only testing, interpreted by your care team, can tell you which type of diabetes you have.

What LADA Is

LADA shares its cause with type 1 diabetes: the immune system attacks the insulin-producing beta cells in the pancreas. The difference is pace. In LADA the loss of insulin production is slow, so for a time after diagnosis many people still make enough insulin that they do not need to inject any.

The American Diabetes Association classifies LADA within type 1 diabetes, as autoimmune diabetes that progresses slowly, and notes there is ongoing debate about whether it should carry its own name. You will also see it called "type 1.5" informally. An international expert panel estimated in 2020 that LADA accounts for 2 to 12% of all adult-onset diabetes, with the range depending on the population studied and how cases were identified.

Why It Gets Mistaken for Type 2

At diagnosis, LADA looks like type 2. The person is an adult, and they do not need insulin right away — the feature most people associate with type 2. So that is the label they get, and treatment starts accordingly.

Telling the two apart is genuinely hard. The ADA notes that type 1 in adults can start more variably than in children, without the classic symptoms, and sometimes with a temporary period of needing less insulin than expected. Its guidance on investigating suspected type 1 in newly diagnosed adults says no single clinical feature confirms it. The features that discriminate best are:

• Diagnosis before age 35
• A lower body weight (BMI under 25)
• Unintentional weight loss
• Ketoacidosis
• Very high glucose at diagnosis, above 360 mg/dL (20 mmol/L)

Features people often assume are telling — a family history of diabetes, other autoimmune conditions, or the classic thirst and frequent urination — turn out to be weak signals on their own.

How LADA Is Diagnosed

The test that separates LADA from type 2 looks for the antibodies behind the autoimmune attack. The ADA recommends GAD antibodies (glutamic acid decarboxylase) as the first test; if that is negative, IA-2 and ZnT8 antibodies can follow where they are available. The ADA also cautions that relying on a single imperfect antibody test can misclassify some people who really have type 2, so results are read alongside the rest of the picture.

A second test, C-peptide, estimates how much insulin your own pancreas is still making. It does not diagnose LADA by itself, but it is what shapes treatment.

How It Is Treated

There are few large clinical trials in LADA, so the 2020 expert panel built its recommendations on existing type 2 guidance, adjusted for autoimmune diabetes, and organized them around C-peptide:

• Low C-peptide (below 0.3 nmol/L): treat as type 1, with a multiple-dose insulin regimen.
• In between (0.3 to 0.7 nmol/L): a gray area. A modified type 2 approach, with insulin considered in combination with other treatments.
• Higher (above 0.7 nmol/L): a modified type 2 approach, with C-peptide monitored over time to adjust treatment as things change.

The panel also advised screening for LADA in people newly diagnosed with diabetes who do not need insulin, and called for large randomized trials to fill the evidence gaps.

Why the Right Label Matters

Because LADA is autoimmune, insulin production can keep falling over time. That is why the expert panel recommends monitoring C-peptide and adjusting treatment as it changes, rather than setting a plan once. Knowing the diagnosis early means a later move to insulin is expected rather than a surprise — and glucose that keeps rising despite treatment gets explained, not blamed on effort.

It also matters for medicines. SGLT2 inhibitors are a common type 2 treatment, but the 2024 international consensus on hyperglycemic crises does not recommend them for type 1 diabetes, given the risk of euglycemic DKA — ketoacidosis without very high glucose. If you have LADA and take one, raise it with your care team.

Questions Worth Asking

If your diabetes is not behaving the way type 2 is supposed to, these are fair questions to bring to an appointment:

• Have I been tested for diabetes antibodies, such as GAD?
• Would a C-peptide test help decide my treatment?
• How will we know if my own insulin production is dropping?
• Are any of my current medicines a concern if this turns out to be autoimmune?

Where SweetLife Fits

SweetLife works whether or not you take insulin. You can log readings and meals, sync a CGM through Apple Health or Medtronic CareLink, and follow your time in range and estimated A1C over months. With a condition that changes slowly, that long view is what helps: a gradual rise is far easier to spot, and to bring to an appointment, when months of data sit in one place.

The Short Version

LADA is autoimmune diabetes that starts slowly in adults and is often first labeled type 2. It makes up an estimated 2 to 12% of adult-onset diabetes. Antibody testing, starting with GAD, identifies it, and C-peptide guides treatment, which may need to change as insulin production falls. If your diabetes is not behaving like type 2, ask about testing.

Sources

• Buzzetti R, Tuomi T, Mauricio D, et al. Management of Latent Autoimmune Diabetes in Adults: A Consensus Statement From an International Expert Panel. Diabetes. 2020;69(10):2037–2047. doi.org/10.2337/dbi20-0017
• American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024. Diabetes Care. 2024;47(Suppl 1):S20–S42. doi.org/10.2337/dc24-S002
• Umpierrez GE, Davis GM, ElSayed NA, et al. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report. Diabetes Care. 2024;47(8):1257–1275. doi.org/10.2337/dci24-0032