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.

Sunday, July 6, 2014

Wrong Assumptions Lead to False Conclusions: Diabetes Rising by Dan Hurley

Dan Hurley, author of the 2011 book Diabetes Rising and diagnosed with Type 1 diabetes at age 18, makes several substantive errors in his book that lessen the credibility of his “investigative journalism,” in my opinion.  Mr. Hurley (1) incorrectly assumes that ancient descriptions of diabetes were of Type 2 diabetes because those descriptions involved adults not children,  2) promotes Dr. Terence Wilkin’s assertion that Type 1 diabetes and Type 2 diabetes are on a continuum of diabetes, and (3) says that a once rare disease has become a pandemic.  All three are not true.  Although the book is a fascinating read, these fundamental errors lessen the impact of his narrative—incorrect assumptions lead to false conclusions.

New-Onset Type 1 Diabetes Occurs in Both Adults and Children

Mr. Hurley opens Chapter 1 of Diabetes Rising with descriptions of diabetes from ancient times.  Early descriptions of diabetes, including Aretaeus of Cappadocia, clearly described what is now called Type 1 diabetes (polyuria, polydipsia, rapid weight loss and swift death).  But Mr. Hurley concludes that these descriptions must be of Type 2 diabetes, for the reason that the descriptions were of "adults, not children, whose symptoms typically came on slowly (as they often do in type 2), not quickly (as they almost always do in type 1.")  And yet new-onset Type 1 diabetes is diagnosed throughout the lifespan and is not a childhood disease, so it is no surprise that Aretaeus of Cappadocia described adults.  Mr. Hurley says, “Nearly all the early description of diabetes are plainly of Type 2, involving adults, not children…” and Mr. Hurley wonders why these early physicians did not note that the patients were obese (“yet they never noticed that the leading risk factor for the disease is obesity” and “Rather than suspecting them of being dull-witted when it comes to something so obvious [obesity].”)  But the early physicians were not dull-witted; they were describing the disease now called Type 1 diabetes, and they did not mention weight other than to remark on the thinness of patients, because the patients were not obese—obesity is not a risk factor for Type 1 diabetes.

In Principles of Diabetes Mellitus, 2nd Edition (Leonid Poretsky, MD, Editor), the authors in Chapter 1 write:  “A medical condition producing excessive thirst, continuous urination, and severe weight loss has interested medical authors for over three millennia.  Unfortunately, until the early part of the twentieth century the prognosis for a patient with this condition was no better than it was over 3000 years ago.  Since the ancient physicians described almost exclusively cases of what is today known as Type 1 diabetes mellitus [emphasis mine], the outcome was invariably fatal.”  The early descriptions of diabetes, including the vivid description by Aretaeus the Cappadocian, clearly are of what we know today as Type 1 diabetes.

Regarding age of onset, let’s look at the facts:  actress and Chair of JDRF International Mary Tyler Moore was diagnosed with Type 1 diabetes at age 33.  Dr. Kenneth Moritsugu, former acting U.S. Surgeon General, was diagnosed with Type 1 diabetes at age 49.  Dr. Anne Peters, a prominent endocrinologist, editor of The Type 1 Diabetes Sourcebook, and co-author of the American Diabetes Association’s (ADA’s) 2014 position statement “Type 1 Diabetes Through the Life Span: A Position Statement of the American Diabetes Association” says that the oldest patient she has diagnosed with Type 1 diabetes was 92 years old.  Dr. Irl Hirsch, a prominent diabetes researcher who has Type 1 diabetes himself, says the oldest patient that he has diagnosed with Type 1 diabetes was 86 years old.  The U.S. Centers for Disease Control and Prevention (CDC) information on the prevalence and incidence of Type 1 diabetes indicates that the majority of new onset Type 1 diabetes is seen in adults[1].  Dr. Elliott Joslin, in 1934, noted that the incidence of diabetes in lean individuals was relatively constant in each decade of life, but that diabetes in the obese was related to older age. A book published in 1958 (“How to Live with Diabetes” by Henry Dolger, M.D. and Bernard Seeman) that states that “[Type 1] diabetes is almost three times more frequent among young adults than among youngsters.”  Mr. Hurley devotes considerable ink to the landmark Diabetes Control and Complications Trial (DCCT), whose study subjects all have Type 1 diabetes, but neglects to mention that many of the 1,441 study subjects were adults when they were diagnosed with Type 1 diabetes.  On page 20, Mr. Hurley neglects to mention that both emaciated diabetic children but also emaciated diabetic adults under Frederick M. Allen’s care were saved by the discovery of insulin in 1922 ("virtually overnight emaciated diabetic children who had been clinging to life by the thread....were able to put on pounds and regain their strength" with no mention of the adults who were also saved).  It is an outdated myth that Type 1 diabetes is “juvenile” diabetes and is a childhood disease.

Type 1 Diabetes and Type 2 Diabetes are Different Diseases

In much of Diabetes Rising, Mr. Hurley does make the distinction between the two diseases, Type 1 diabetes and Type 2 diabetes, but Chapter 5 is devoted to Dr. Terence J. Wilkin's "accelerator hypothesis," and Dr. Wilkin's "audacious idea that type 1 and type 2 are really one disease, distinguishable only in degrees."  However, early physicians understood that “diabetes mellitus” represented several diseases.  In the 1970s, Type 1 diabetes was determined to be an autoimmune disease, the result of an immune-mediated destruction of the beta cells, and distinguished from Type 2 diabetes which is not autoimmune[2].  As stated in The Type 1 Diabetes Sourcebook (ADA/JDRF 2013), the pathophysiology of the two diseases [T1D and T2D] 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.  Sue Kirkman MD, professor of medicine at University of North Carolina and one of four authors of the ADA position statement “Type 1 Diabetes Through the Life Span: A Position Statement of the American Diabetes Association” says “Type 1 diabetes is a completely different disease than Type 2 and needs to be treated as such.”  Type 1 diabetes is an autoimmune disease, and the presence of autoantibodies confirms Type 1 diabetes.  Yet to justify that Type 1 and 2 are really the same disease, Dr. Wilkin cited studies that found that 20 to 29 percent of people with Type 2 diabetes had at least one of the autoantibodies normally associated with type 1 diabetes (Diabetes Rising, p. 98)[3].  What Dr. Wilkin fails to recognize, and Mr. Hurley did not correct, is that the presence of autoantibodies in a person diagnosed with “Type 2” diabetes means that the person has been misdiagnosed and has Type 1 diabetes, since autoantibodies are never present in Type 2 diabetes by definition—autoimmune diabetes is Type 1 diabetes.  The problem of misdiagnosis (adults with new-onset Type 1 diabetes who are misdiagnosed as having Type 2 diabetes, based on age not etiology) is enormous, but only recently being recognized (see for example the Wall Street Journal’s “Wrong Call:  The Trouble Diagnosing Diabetes,” August 2012).   In the Wall Street Journal article, Robin Goland, co-director of the Naomi Berrie Diabetes Center at Columbia University Medical Center in New York, states “Most of my [adult Type 1 patients] have been misdiagnosed as having Type 2 diabetes.”  Michael J. Haller MD, in Type 1 Diabetes Sourcebook (ADA/JDRF, 2013), says “Importantly, adults with LADA [latent autoimmune diabetes in adults or slowly progressive Type 1 diabetes] may represent an additional 10% of those adults incorrectly diagnosed with Type 2 diabetes.”  It shows a lack of scientific rigor to fail to differentiate between Type 1 and Type 2 diabetes; they are different diseases, not different forms of one disease, and the two diseases have different genetics, causes, treatments, and potential cures.

Diabetes as a Rare Disease

It is sensationalistic and sells books to say that a once rare disease, diabetes, is now an epidemic or pandemic, but it is false.  As I substantiated previously, early descriptions of the once rare disease were of Type 1 diabetes, and Type 1 and Type 2 diabetes are altogether different diseases.  Although rates of Type 1 diabetes have increased (especially if the misdiagnosed are correctly included in the statistics for T1D), it is Type 2 diabetes that is the epidemic.  The incidence of Type 2 diabetes has dramatically increased in recent decades, much more rapidly than Type 1 diabetes.  The once rare disease, Type 1 diabetes, has not become the pandemic of Type 2 diabetes.

The problem of misdiagnosis is enormous and tragic—it typically results in the withholding of life-saving care for patients with a treatable disease.  Books such as Diabetes Rising contribute to the misinformation surrounding Type 1 diabetes; by promoting these factual errors, Mr. Hurley reduces the impact of his work, which is unfortunate because much of Diabetes Rising is a rarely seen, in-depth look at the realities of Type 1 diabetes and Type 2 diabetes.

[1] 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).  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. 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 non-autoimmune diabetes (Type 2 diabetes, monogenic diabetes, etc.).
[2] 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)).” 
[3] Autoantibodies include glutamic acid decarboxylase autoantibodies (GAD), islet cell cytoplasmic autoantibodies (ICA), insulinoma-associated 2 autoantibodies (IA-2), insulin autoantibodies (IAA), and zinc transporter 8 autoantibodies (ZnT8).  IAA can only be tested if exogenous insulin has not yet been used.  Other autoantibodies may exist but have not yet been identified.