In 2016, I attended an amazing conference for those with Type 1 diabetes and their loved ones, CarbDM, held in the San Francisco Bay Area. The opening presentations illustrate a simple cause and effect relationship: if the medical community and diabetes organizations promote that Type 1 diabetes is a childhood disease, those who acquire Type 1 diabetes as adults are misdiagnosed as having Type 2 diabetes, an altogether different disease, and given inappropriate treatment. It is important to know that most new-onset Type 1 diabetes is seen in adults. Speakers at the conference, world-renowned endocrinologists and diabetologists, referred to Type 1 diabetes as a childhood disease and only spoke of work with children. Ironically, the opening speaker, news reporter Keba Arnold, spoke about how she was diagnosed with Type 1 diabetes as an adult, although she was initially misdiagnosed as having Type 2 diabetes despite having no risk factors and having a brother who has Type 1 diabetes. This was a clear example of a simple case of cause (promote Type 1 diabetes as a childhood disease) and effect (adults with new-onset Type 1 diabetes are misdiagnosed as having Type 2 diabetes).
A recent article in Diabetes Spectrum entitled “Recognizing and Appropriately Treating Latent Autoimmune Diabetes in Adults (LADA)” (Diabetes Spectrum 2016 Nov; 29(4):249-252) makes simple but important points about adult-onset Type 1 diabetes. Unfortunately, the authors do not address the fact that adult-onset Type 1 diabetes can be both rapid onset (which happened to me at age 35) or slow onset (LADA), and that for women it can be precipitated by pregnancy. Nonetheless, here are highlights:
- LADA is Type 1 diabetes but is often misdiagnosed as Type 2 diabetes because of a lack of awareness and a lack of standardized diagnostic criteria.
- Misdiagnosis results in insufficient glycemic control and harm to patients.
- It is imperative to establish distinct practice guidelines for the diagnosis and treatment of adult-onset Type 1 diabetes and for providers to recognize this clinical scenario as one that requires special testing (autoantibody testing) to establish a proper diagnosis and thus improve patient safety and treatment efficacy.
- Incorrect diagnosis can delay proper treatment (insulin therapy), exposing patients to potential adverse effects from ineffective Type 2 drugs, slowing progress toward normoglycemia, and ultimately increasing the risk of long-term complications.
- Patients are often misdiagnosed due to the use of arbitrary screening criteria such as age.
- It is important to develop standardized guidelines for LADA to improve diagnostic and treatment quality, help providers become more aware of LADA, and decrease the risk of harm to patients from inadequate treatment.
Research studies have shown that ~10% of people diagnosed with “Type 2” diabetes are autoantibody positive, have been misdiagnosed, and in fact have Type 1 autoimmune diabetes. For example, Robin Goland, co-director of the Naomi Berrie Diabetes Center at Columbia University Medical Center in New York, says that most of her patients with adult-onset Type 1 diabetes were misdiagnosed as having Type 2 diabetes.
An awareness campaign and standardized guidelines for identification and treatment of adult-onset Type 1 diabetes are urgently needed. I am grateful to the researchers who wrote the Diabetes Spectrum article, who are advocating on behalf of those with adult-onset Type 1 diabetes and the misdiagnosed. It is interesting to note that the authors of this article are associated with a university pharmacy college and are not physicians. One is left to wonder how much of a difference we could make in the effort to ensure correct diagnosis if all care providers worked together to share ideas, challenge assumptions, and advocate for patients.
 The U.S. Centers for Disease Control and Prevention’s (CDC’s) most current information on the prevalence and incidence of Type 1 diabetes comes from Diabetes in America, Chapter 3, “Prevalence and Incidence of Insulin-Dependent Diabetes” (Diabetes in America, Second Edition, 1995). Although people who use that reference as a source of incidence statistics state that there are about 30,000 new cases of Type 1 diabetes each year and that half of those cases are children; in fact, that source states that children (<20 years of age) account for 13,171 cases and adults (>20 years of age) account for 16,542 cases, for a total of 29,713 new cases of Type 1 diabetes per year, 56% seen in adults. Furthermore, that source states that there is an unknown number of adults identified as having Type 2 diabetes who actually have slowly progressive Type 1 diabetes. Numerous studies since the first published in 1977 provide evidence that ~10% of cases of “Type 2” diabetes are in fact Type 1 diabetes, based on autoantibody testing (GAD, ICA, IA-2, IAA, and ZnT8), and researchers using genetic data have shown that the majority of new-onset Type 1 diabetes occurs in adults. In “The Type 1 Diabetes Sourcebook” (ADA/JDRF 2013) Michael Haller MD states, "Adults with LADA [latent autoimmune diabetes in adults or slowly progressive Type 1 diabetes] may represent 10% of those adults incorrectly diagnosed with Type 2 diabetes. Clinicians treating adults must be aware of the need to screen for LADA, particularly in their patients with relatively low BMI."
 From “The Type 1 Diabetes Sourcebook” (ADA/JDRF 2013), “Adult patients can vary greatly at presentation, from a more acute picture, with DKA and marked hyperglycemia, to a more gradual course such as is often seen in latent autoimmune diabetes in adults (LADA).”
 The Diabetes Spectrum article does not mention autoimmune gestational diabetes, but another very dangerous situation is when the stress of pregnancy is “the straw that broke the camel’s back” and pushes a woman over the edge into overt Type 1 diabetes. Most medical literature only associates gestational diabetes with Type 2 diabetes, yet fully 10% of women with GDM have the autoimmune markers for Type 1 diabetes. Misdiagnosis can lead to fetal death.