Type 2 diabetes in children can have an autoimmune component

Most practitioners and parents think of type 2 diabetes (T2DM) as a metabolic disorder that emerges when the pancreas can no longer keep up with the increasing need for insulin as receptor resistance grows worse. There is growing evidence that T2DM in children and adults is in many cases complicated by the same autoimmune phenomena as in type 1 diabetes. A study just published in the journal Diabetes Care adds to the evidence. The authors set out to:

“…determine the frequency of islet cell autoimmunity in youth clinically diagnosed with type 2 diabetes and describe associated clinical and laboratory findings.”

They screened 1,206 children ages (10-17) who were known to have type 2 diabetes for GAD-65 and insulinoma-associated protein 2 autoantibodies using the new National Institute of Diabetes and Digestive and Kidney Diseases/National Institutes of Health (NIDDK/NIH) standardized assays, performed physical examinations, and measured fasting lipids, C-peptide, and HgbA1C. What did the data show?

“Of the 1,206 subjects screened and considered clinically to have type 2 diabetes, 118 (9.8%) were antibody positive…Diabetes autoantibody (DAA) positivity was significantly associated with race, with positive subjects more likely to be white (40.7 vs. 19% and male (51.7 vs. 35.7%. BMI, BMI z score, C-peptide, A1C, triglycerides, HDL cholesterol, and blood pressure were significantly different by antibody status. The antibody-positive subjects were less likely to display characteristics clinically associated with type 2 diabetes and a metabolic syndrome phenotype…”

A clinical ‘pearl’ embedded here is that if a youth with T2DM does not have the characteristics of metabolic syndrome (overweight, etc.), there is strong suspicion of an autoimmune component to their condition. This must, however, be determined by a blood test for the autoantibodies. The authors conclude:

“Obese youth with a clinical diagnosis of type 2 diabetes may have evidence of islet autoimmunity contributing to insulin deficiency. As a group, patients with DAA have clinical characteristics significantly different from those without DAA. However, without islet autoantibody analysis, these characteristics cannot reliably distinguish between obese young individuals with type 2 diabetes and those with autoimmune diabetes.”

Neurological disease with GAD antibodies and gluten sensitivity

GAD (glutamic acid decarboxylase) antibodies are expressed in type 1 (autoimmune) diabetes, adrenal failure (Addison disease), autoimmune thyroid diseases, premature ovarian failure, myasthenia gravis, pernicious anemia, Stiff-man syndrome and a number of other disorders. An informative study recently published in Acta Neurologica Scandinavica documents the link between these conditions and gluten sensitivity. The authors state:

“The high prevalence of gluten sensitivity in patients with stiff-person syndrome (SPS) lead us to investigate the relationship between gluten sensitivity and GAD-antibody-associated diseases.”

They used ELISA assays for GAD antibodies and serological markers of gluten sensitivity that generated compelling data:

“”Six of seven (86%) patients with SPS were positive for anti-GAD…This compared with 9/90 (11%) patients with idiopathic sporadic ataxia…16/40 (40%) patients with gluten ataxia…and 6/10 patients with type 1 diabetes only…”

Note that the serological tests for gluten sensitivity are a blunt instrument—only 40% of confirmed cases of gluten ataxia were recognized. The abundance of false negatives is why the gluten gene sensitivity test is so valuable.

Additionally, the authors found that…

“The titre of anti-GAD reduced following the introduction of a gluten-free diet in patients with SPS who had serological evidence of gluten sensitivity.”

Their conclusion is simply stated:

“These findings suggest a link between gluten sensitivity and GAD antibody-associated diseases.

This study is especially interesting in connection with earlier research published in the journal Psychiatry. The authors set out to investigate the role of GAD antibodies in schizophrenia and related disorders:

“We hypothesized that GAD antibodies are increased in patients with chronic psychotic disorders. The aim of this pilot study was to compare the level of GAD antibodies in patients with chronic psychotic disorders with normal controls.”

By way of background they note that:

“The role of GABAergic neurotransmission in epilepsy, anxiety disorders, schizophrenia, and premenstrual dysphoric disorder has been a subject of some recent investigations. Absence of structural abnormalities in the brains of most patients with chronic psychotic disorders has always raised suspicion for an alternative pathogenesis and a possible functional disturbance at the neuronal/cellular level. Glutamic acid decarboxylase (GAD)…is involved in the formation of gamma aminobutyric acid (GABA) a central inhibitory neurotransmitter of the nervous system. Antibodies to GAD may impair GABA formation or inhibitory function.

What did the data show?

“Serum levels of GAD antibodies in 12 patients with chronic psychotic disorders (schizophrenia and schizoaffective disorders) and 10 age-matched healthy control subjects were evaluated… Antibodies to GAD in patients with chronic psychotic disorders have a higher mean than nonpatient control individuals.”

The authors’ conclusion alerts the practitioner to be on the lookout:

Antibodies to GAD65 are peripherally present in patients with chronic psychotic disorders (schizophrenia/schizoaffective disorders)... The presence of such antibodies also suggests a possible role for autoimmune mechanism in the pathogenesis of these disorders. In summary, from a practicing psychiatrist’s point of view, measurements of antibodies to GAD65 could potentially be used to screen for chronic psychotic disorders and for diabetes mellitus very early on in the disease process.”

GAD (glutamic acid decarboxylase) produces GABA, the most abundant inhibitory (calming) neurotransmitter in the body. Suboptimal levels can manifest as anxiety, insomnia, hyperarousal, panic, feeling overwhelmed, disorganized attention, restlessness, worry, tension, inner excitability, inability to relax, etc.