The Patient-Centered Approach for the Person with Adult-Onset Type 1 Diabetes
by Melitta Rorty, M.S.
Adults with new-onset Type 1 diabetes frequently experience the problem of incorrect or delayed diagnosis which can result in the rapid onset of diabetic complications and even death due to diabetic ketoacidosis (DKA). The aim of this position paper is to improve diagnosis and treatment of adult patients with Type 1 diabetes. New-onset Type 1 diabetes in adulthood is far more prevalent than childhood-onset Type 1 diabetes, but the myth that Type 1 diabetes is a childhood disease combined with the rising epidemic of Type 2 diabetes often means that adults with new-onset Type 1 diabetes are incorrectly diagnosed as having Type 2 diabetes, an altogether different disease. Patients who are misdiagnosed and treated as if they have Type 2 diabetes are frequently undertreated with medications that do not help their medical condition. As stated in a Wall Street Journal article on the problem of misdiagnosis (“Wrong Call: The Trouble Diagnosing Diabetes,” August 2012), "Most of my [adult Type 1 patients] have been misdiagnosed as having Type 2," says Robin Goland, co-director of the Naomi Berrie Diabetes Center at Columbia University Medical Center in New York. "Once the right diagnosis is made the patient feels much, much better, but they are distrustful of doctors and who could blame them?"
Here are four stories of patients with adult-onset Type 1 diabetes who were initially misdiagnosed as having Type 2 diabetes, and what they want the medical community to know:
- At age 30, soon after she retired as professional ballet dancer, Kris was misdiagnosed as having Type 2 diabetes and told by her doctor to lose weight (at 5’6” tall, Kris weighed less than 100 pounds) and exercise more. Her doctor scolded her when the “lifestyle changes” that he ordered did nothing for her, because in her doctor’s mind the problem was that Kris was not following his directives. Kris went into diabetic ketoacidosis, lapsed into a coma, and thankfully was found by friends and rushed to the emergency room. Initially in the emergency room the doctors accused her of not following her treatment protocol thereby bringing DKA upon herself, until they called in an endocrinologist who realized she had been misdiagnosed and given incorrect treatment. In the ER, the endocrinologist correctly diagnosed Kris as having Type 1 diabetes and she was treated with exogenous insulin.
- Michael, a competitive bicyclist, was misdiagnosed as having Type 2 diabetes at age 42. Acquaintances advised Michael to get autoantibody testing, which his doctor initially refused to perform. Finally, when his doctor reluctantly ordered the autoantibody tests and the tests came back positive, Michael’s doctor sent him a letter via U.S. mail saying he “might” have Type 1 diabetes. Due to the delay in performance of autoantibody testing and the resulting delay in obtaining a correct diagnosis, Michael was not given exogenous insulin until 12 months after his initial misdiagnosis.
- Marybeth was hospitalized in DKA at the age of 60, but incorrectly diagnosed as having Type 2 diabetes based on age, not etiology. Marybeth was fit, active, normal weight, and displayed extreme sensitivity to insulin in the ER. Six months prior to hospitalization, Marybeth’s fasting blood glucose was 74 mg/dl at a health screening. Marybeth says, “If I had followed my hospital discharge instructions I would probably be dead” and “Clinicians need to be brought up to date on the incidence of Type 1 diabetes in adults. They need to look at the whole picture. Emergency room doctors especially need to use their brains not just a blindly follow a Standard Operating Procedure (SOP).”
- Jen, misdiagnosed at age 22, says, “I hope that more medical professionals realize how misdiagnosing adults with type 2 diabetes instead of type 1 can be dangerous and carries a very significant mental and physical toll on the newly diagnosed diabetic.”
Every patient deserves a careful medical analysis including evidence-based best practices to achieve correct diagnosis and treatment; the following concepts illustrate the patient-centered approach:
1) The patient deserves to be correctly diagnosed: If an adult is diagnosed with diabetes (fasting blood glucose greater than 125 mg/dl or hemoglobin A1c 6.5 or greater) and does not appear to fit a more typical profile for Type 2 diabetes (i.e., the adult is not overweight, does not have abdominal obesity, is not insulin resistant, does not have a family history of Type 2 diabetes, and does not have metabolic syndrome), testing to differentiate the type of diabetes should be performed. Testing should also be performed if a patient is not responding to Type 2 protocols. Autoantibody testing can be used to differentiate between Type 1 autoimmune diabetes and diabetes due to other causes. Autoantibody testing includes glutamic acid decarboxylase autoantibodies (GADA), insulin autoantibodies (IAA), insulinoma-associated autoantibodies (IA-2), and zinc transporter autoantibodies (ZnT8)), and the c-peptide test is also useful but not definitive. If the person is autoantibody positive, he/she has Type 1 diabetes. Often medical doctors and researchers will say that autoantibody testing is too expensive (non-discounted, out-of-pocket cash price of approximately $750 for the Mayo Clinic “Diabetes Mellitus Type 1 Evaluation Panel” (does not include ZnT8)), however, misdiagnosis often results in DKA or early diabetic complications, which are exponentially more expensive and largely avoidable. Diabetes researcher R. David Leslie MD says, "The best way to identify autoimmune diabetes is to assess diabetes-associated autoantibodies [GAD, IAA, IA-2, ZnT8], which represent the only relevant categorical trait." An American Diabetes Association position statement affirms, “Consider measurement of pancreatic autoantibodies to confirm the diagnosis of Type 1 diabetes.”
2) The newly diagnosed person with Type 1 diabetes needs appropriate treatment with exogenous insulin: Intensive insulin therapy should begin as quickly as possible in the newly diagnosed adult with Type 1 diabetes. The correct treatment for Type 1 diabetes, at whatever age it is diagnosed, is exogenous insulin as early as possible, to control glucose levels, prevent further destruction of residual beta cells, reduce the possibility of diabetic complications, and prevent death from DKA. Although some doctors say that the correct diagnosis is not necessary because the treatment of the hyperglycemia is what is important, the patient stories above demonstrate why being correctly diagnosed is so vital. Instead of correctly treating hyperglycemia, it is the patients’ typical experience that medical doctors will blame the [Type 1] patient for not following the doctors’ directives [for treatment of Type 2 diabetes], instead of giving appropriate treatment for Type 1 diabetes (exogenous insulin).
3) The newly diagnosed adult needs appropriate Type 1-specific education: An adult who is newly diagnosed with Type 1 diabetes should receive Type 1 diabetes-specific education, not Type 2 diabetes education. Type 2 diabetes is a different disease with different genetics, causes, treatments, and potential cures.
The American Diabetes Association/JDRF Type 1 Diabetes Sourcebook (Anne Peters MD and Lori Laffel, MD, MPH, Editors, 2013) includes important information about the diagnosis and treatment of people with adult-onset Type 1 diabetes:
- Patients with evidence of autoimmunity have Type 1 diabetes.
- There is no authoritative source for the incidence of Type 1 diabetes in adults in the United States population. However, Type 1 diabetes is not a childhood disease and may be diagnosed into adulthood with an additional peak in the sixth and seventh decades of life.
- Adults developing Type 1 diabetes may follow a less precipitous course with few or no symptoms and an elevated glucose level identified incidentally on routine blood work. These individuals may be treated (unsuccessfully) with oral agents [for Type 2 diabetes] before it is determined that they are actually patients with evolving Type 1 diabetes who need treatment with insulin.
- 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). For those presenting acutely as well as those presenting more indolently, starting insulin is the mainstay of therapy.
- We want [medical] providers to know that patients with Type 1 diabetes are not the same as patients with Type 2 diabetes; thus, we describe the specific approaches for patients with Type 1 diabetes across the life span.
- The pathophysiology of the two diseases [Type 1 diabetes and Type 2 diabetes] differ on a basic pathophysiologic level such that Type 1 diabetes is marked by insulinopenia while Type 2 diabetes is characterized by obesity, hyperinsulinemia, insulin resistance, and relative insulinopenia.
The Hippocratic Oath says, “First do no harm.” Medical doctors already know how to effectively treat Type 1 diabetes in children and teenagers; that excellence in care should also be applied to adults with new-onset Type 1 diabetes. When a child is diagnosed with Type 1 diabetes, the medical community springs to action on the child’s behalf, because Type 1 diabetes is a serious, life-threatening disease. Kids who are diagnosed with Type 1 diabetes are shown great compassion, and the disease is acknowledged to be profoundly life-altering. Yet often it appears that adults are not shown the same respect. For patients with adult-onset Type 1 diabetes, the person should be correctly diagnosed, treated with exogenous insulin, acknowledged as having a life-threatening disease, and treated with compassion.
About the Author: Melitta Rorty, M.S., was diagnosed with Type 1 diabetes at age 35, although she was initially misdiagnosed as having Type 2 diabetes based on age not etiology. She is a member of Diabetes Advocates (Diabetes Hands Foundation) and her Adult Onset Type 1 Diabetes website can be found at www.adultt1diabetes.blogspot.com. Acknowledgment: Melitta appreciates the review and input on this position paper by her cousin, Family Practice physician Diane E. Dakin, MD; any errors are those of the author.
 Type 1 diabetes in adults can be acute-onset or slowly progressive. Slowly progressive Type 1 diabetes is sometimes called latent autoimmune diabetes in adults (LADA) or Type 1.5 diabetes. More recently, diabetes researchers have discouraged the use of the term latent autoimmune diabetes in adults, because LADA is not a latent disease.
 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 have slowly progressive Type 1 diabetes (Michael J. Haller MD, in Type 1 Diabetes Sourcebook (ADA/JDRF, 2013), says “Importantly, adults with LADA may represent an additional 10% of those adults incorrectly diagnosed with Type 2 diabetes.”) The number of people with slowly progressive Type 1 diabetes is quite large, consistently about 10% of “Type 2” diabetes based on autoantibody testing (for example, the first study that demonstrated that about 10% of people with “Type 2” diabetes are autoantibody positive was published in The Lancet in 1977. In the UKPDS, about 10% of people diagnosed with “Type 2” diabetes were autoantibody positive and had been misdiagnosed). Clinicians use autoantibody tests to distinguish between Type 1 autoimmune diabetes and nonautoimmune diabetes (Type 2 diabetes, monogenic diabetes, etc.).
 IAA can only be used if the person has never received exogenous insulin.
 From The Type 1 Diabetes Sourcebook, “It is often unappreciated that many individuals with Type 1 diabetes will have significant amounts of C-peptide, representing residual beta cell function. The standard teaching that Type 1 diabetes is defined as complete absence of beta cells is inaccurate and is a disservice to both patients and providers. Among 411 participants in the Joslin Medalists study (those with T1D greater than or equal to 50 years), 67.4% still had detectable C-peptide.” Pages 26 and 27.
 The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (ADA/WHO), as published in American Diabetes Association medical journals, says, "Although the specific etiologies of [Type 2] diabetes are not known, autoimmune destruction of beta-cells does not occur." The Expert Committee’s definition of Type 1 diabetes clearly encompasses all autoimmune diabetes, regardless of age (“Type 1 diabetes results from a cellular-mediated autoimmune destruction of the beta-cells of the pancreas. In Type 1 diabetes, the rate of beta-cell destruction is quite variable, being rapid in some individuals (mainly infants and children) and slow in others (mainly adults)).”
 “Type 1 Diabetes Through the Life Span: A Position Statement of the American Diabetes Association.” Diabetes Care, June 16, 2014. Jan L. Chiang, M. Sue Kirkman, Lori M.B. Laffel, and Anne L. Peters.
 In the Diabetes Control and Complications Trial (DCCT), all subjects with adult-onset Type 1 diabetes had some residual beta cell function (Bernard Zinman M.D., personal communication). Those who were assigned to the intensive insulin therapy group were slower to lose residual beta cell function than the conventional therapy group (risk reduction 57%). Clearly, early intensive insulin therapy has enormous benefit. As demonstrated in the DCCT, “intensive therapy for Type 1 diabetes helps sustain endogenous insulin secretion, which, in turn, is associated with better metabolic control and lower risk for hyperglycemia and chronic complications.” LADA researchers in Japan (Kobayashi et al, 2002) have conclusively demonstrated that better preservation of beta cell function occurs with exogenous insulin compared to sulfonylureas, and that sulfonylureas hasten beta cell destruction. Doctors may incorrectly and ineffectively use Type 2 therapies in new-onset Type 1 diabetes, but the correct therapy is intensive insulin therapy.