The Problem

It is time that the full scope of Type 1 diabetes is acknowledged, which includes millions of adults who are too frequently misdiagnosed as having Type 2 diabetes, an altogether different disease.

Friday, March 7, 2014

Bill of Rights for People with Adult-Onset Type 1 Diabetes Or “A Manifesto for the Misdiagnosed”

There are many names for adult-onset Type 1 diabetes, including latent autoimmune diabetes in adults (LADA)[1], Type 1.5 diabetes, and slowly progressive Type 1 diabetes[2].  Although the majority of new-onset Type 1 diabetes always has been seen in adults[3], the myth that Type 1 diabetes is a childhood disease often means adults with Type 1 are misdiagnosed as having Type 2 diabetes and/or given substandard treatment.  Here is my manifesto:

·         Correct diagnosis:  If an adult is diagnosed with diabetes 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), the person should be tested to see if he/she has Type 1 autoimmune diabetes.  The gold-standard test for Type 1 diabetes is autoantibody testing (glutamic acid decarboxylase autoantibodies (GADA), islet cell autoantibodies (ICA), insulin autoantibodies, insulinoma-associated (IA-2) autoantibodies, 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.

·         Insulin treatment:  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 diabetic ketoacidosis (DKA). [4]

·         Appropriate 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.

·         Autoimmune gestational diabetes:  Many if not most of medical professionals are not aware that gestational diabetes may be a precursor to Type 1 diabetes, not just Type 2 diabetes.  The stress of pregnancy is "the straw that broke the camel's back" for many women who develop Type 1 diabetes during pregnancy (autoimmune gestational diabetes).  Again, antibody testing can be used to distinguish autoimmune gestational diabetes, and women with autoimmune gestational diabetes should begin intensive insulin therapy immediately.[5]

·         Inclusion in appropriate statistics:  People with adult-onset Type 1 diabetes should be included in statistics addressing prevalence and incidence of Type 1 diabetes.  At the present time, most adult-onset Type 1s are included in figures for the numbers of Type 2 diabetics.   In information distributed to laypeople, the U.S. Centers for Disease Control and Prevention (CDC) and the American Diabetes Association (ADA) consistently say that Type 2 diabetes represents 90-95% of cases of diabetes in America and that Type 1 diabetes represents 5-10% of all cases of diabetes. However, this is incorrect according to ADA’s own peer-reviewed scientific journals. That 90-95% Type 2 statistic includes people with LADA, and according to the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (as published in ADA journals), "Although the specific etiologies of [Type 2] diabetes are not known, autoimmune destruction of beta-cells does not occur."  The National Institutes of Health (NIH (NIDDK)) defines LADA as a condition in which Type 1 diabetes develops in adults.  Furthermore, the Expert Committee’s definition of Type 1 diabetes by the clearly encompasses all autoimmune diabetes, regardless of age, which includes LADA (“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).”)  According to Irl Hirsch M.D., member of the Expert Committee, “The term latent autoimmune diabetes of adults (LADA) as originally described represents perhaps as many as 10­ to 20% of adult-onset patients with diabetes.”  Doing the math, Type 1 diabetes represents about 20% of all people with diabetes.

·         Inclusion in clinical trials:  People with adult-onset Type 1 diabetes should not be excluded from clinical trials for Type 1 diabetes strictly because of age.  For example, Type 1 Diabetes TrialNet excludes many Type 1 diabetics and their families based on age at diagnosis.  Type 1 autoimmune diabetes is diagnosed based on epidemiology, not age; therefore, TrialNet is not truly representative of the full scope of Type 1 diabetes.  Former acting U.S. Surgeon General Dr. Kenneth Moritsugu, who was diagnosed with Type 1 diabetes at age 49, would be excluded from Type 1 Diabetes TrialNet.

All people with Type 1 diabetes deserve to be correctly diagnosed and be given disease-appropriate treatment, yet for many people with adult-onset Type 1 diabetes that is not happening today.

[1] More recently, diabetes researchers have discouraged the use of the term latent autoimmune diabetes in adults, because LADA is not a latent disease.  One group has proposed the term ADASP (autoimmune diabetes in adults with slowly progressive beta cell failure), but this term seems cumbersome.
[2] Some adult-onset Type 1 diabetes is acute onset, similar to what most children experience.  I had acute-onset Type 1 diabetes.
[3] 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 Type 2 diabetes who have slowly progressive Type 1 diabetes.”  In summary, of those new onset Type 1 diabetics who are correctly diagnosed, 56% are adults, and an unknown number of new-onset Type 1 diabetics have been misdiagnosed as having Type 2 diabetes and thus the majority of new onset Type 1 diabetes is seen in adults.
[4] In the Diabetes Control and Complications Trial (DCCT), all subjects with adult-onset Type 1 diabetes had some residual beta cell function (Bernard Zinman MD, DCCT).  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.  In other words, doctors may inappropriately use Type 2 therapies in new-onset Type 1 diabetes, but all scientific studies indicate that the correct therapy is intensive insulin therapy.
[5] In Europe, the literature on gestational diabetes mentions autoimmune gestational diabetes, but in North America the layperson literature doesn't mention it. However, the existence of autoimmune gestational diabetes is widely reported in North American scientific literature (for example, a July 2007 "Diabetes Care" article and also an April 2003 "Diabetes Care" article on GDM). The July 2007 issue of "Diabetes Care" indicated that autoimmune gestational diabetes (new onset Type 1 diabetes) accounts for about 10% of all Caucasian women diagnosed with gestational diabetes (Diabetes Care July 2007 vol. 30 no. Supplement 2 S105-S111 ). It says “A small minority (≤10% in most studies) of women with GDM have circulating antibodies to pancreatic islets (anti-islet cell antibodies) or to β-cell antigens such as GAD (anti-GAD antibodies)” and then notes, “They appear to have evolving type 1 diabetes that comes to clinical attention through routine glucose screening during pregnancy. Whether pregnancy can actually initiate or accelerate islet-directed autoimmunity is unknown.”

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