Antibodies against glutamic acid decarboxylase and indices of insulin resistance and insulin secretion in nondiabetic adults: a cross-sectional study
Received 16 March 2017
Accepted for publication 8 April 2017
Published 8 May 2017 Volume 2017:10 Pages 179—185
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Professor Ming-Hui Zou
Carlos O Mendivil,1,2 Freddy JK Toloza,1 Maria L Ricardo-Silgado,1 Martha C Morales-Álvarez,1 Jose O Mantilla-Rivas,1 Jairo A Pinzón-Cortés,1 Hernán N Lemus1
1School of Medicine, Universidad de los Andes, 2Section of Endocrinology, Fundación Santa Fe de Bogotá, Bogotá, Colombia
Background: Autoimmunity against insulin-producing beta cells from pancreatic islets is a common phenomenon in type 1 diabetes and latent autoimmune diabetes in adults. Some reports have also related beta-cell autoimmunity to insulin resistance (IR) in type 2 diabetes. However, the extent to which autoimmunity against components of beta cells is present and relates to IR and insulin secretion in nondiabetic adults is uncertain.
Aim: To explore the association between antibodies against glutamic acid decarboxylase (GADA), a major antigen from beta cells, and indices of whole-body IR and beta-cell capacity/insulin secretion in adults who do not have diabetes.
Methods: We studied 81 adults of both sexes aged 30–70, without known diabetes or any autoimmune disease. Participants underwent an oral glucose tolerance test (OGTT) with determination of plasma glucose and insulin at 0, 30, 60, 90, and 120 minutes. From these results we calculated indices of insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR] and incremental area under the insulin curve [iAUCins]) and insulin secretion (corrected insulin response at 30 minutes and HOMA beta-cell%). GADAs were measured in fasting plasma using immunoenzymatic methods.
Results: We found an overall prevalence of GADA positivity of 21.3%, without differences by sex and no correlation with age. GADA titers did not change monotonically across quartiles of any of the IR or insulin secretion indices studies. GADA did not correlate linearly with fasting IR expressed as HOMA-IR (Spearman’s r=−0.18, p=0.10) or postabsorptive IR expressed as iAUCins (r=−0.15, p=0.18), but did show a trend toward a negative correlation with insulin secretory capacity expressed by the HOMA-beta cell% index (r=−0.20, p=0.07). Hemoglobin A1c, body mass index, and waist circumference were not associated with GADA titers.
Conclusion: GADA positivity is frequent and likely related to impaired beta-cell function among adults without known diabetes.
Keywords: insulin resistance, autoimmunity, glutamate decarboxylase, latent autoimmune diabetes in adults, beta cell
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