Latent autoimmune diabetes of adulthood (LADA) is a slowly progressive condition in which type 1 diabetes develops in adults, usually after age 30. LADA also displays some characteristics of, and is sometimes misdiagnosed as, type 2 diabetes.

One of the main differences between people with LADA and type 2 diabetes is that LADA patients tend to be younger and thinner. Also, individuals with LADA are usually insulin deficient rather than insulin resistant.

Someone who has been diagnosed with type 2 diabetes, is under age 50, has a lean build and no known relatives with type 2 diabetes may actually have LADA. Physicians can mistake LADA for type 2 diabetes because this form of the disease often responds initially to treatment for type 2 diabetes. Also, individuals with LADA at first lack signs of autoimmunity. LADA, like other forms of type 1 diabetes, is an autoimmune disease in which the body mistakenly attacks the insulin-making cells of the pancreas.

For those misdiagnosed, physicians may become aware of the presence of LADA only when the treatments for type 2 diabetes begin to fail, which can take years. This normally happens when patients can no longer control their glucose (blood sugar) through the standard type 2 treatments of diet, exercise and antidiabetic agents.

LADA is sometimes referred to as type 1.5 diabetes, a term that has also been used for double diabetes and for maturity-onset diabetes of the young (MODY).