The above-cited article has been retracted by the American Diabetes Association (ADA), the publisher of Diabetes. This article was previously the subject of an expression of concern in the August 2016 issue of the journal (1). As noted in the expression of concern, the ADA asked the corresponding author’s institution, the University of Bremen, to review the following issues with the article:
In the erratum for Fig. 5D (2), the “cleaved Caspase 3” panel (lanes 7 and 8 in the original blots and lanes 4 & 5 in the corrected version) closely resembles the “cleaved Casp3” panel in Fig. 3D in the original version of the article (3).
Likewise, in the original article (3), Fig. 5D (lanes 4 and 5) resembles the “cleaved Casp3” panel in Fig. 3D.
In the erratum (2), the “cleaved Caspase 3” panel, lanes 1 and 2, closely resembles a horizontal mirror image of Fig. 2F, TCF7L2 panel, lanes 3 and 4, from a 2009 article by the same author group in Human Molecular Genetics (4). In addition, lanes 4 and 5 of the corrected Fig. 5D in the erratum closely resemble a horizontal mirror image of Fig. 2F, TCF7L2 panel, lanes 1 and 2, of the Human Molecular Genetics article.
The issues described in the August 2016 expression of concern were reviewed by an investigative commission appointed by the University of Bremen. The lead and corresponding authors contacted the ADA in November 2016 to provide a summary of the university’s investigation. According to the authors, the university committee independently reviewed all of the material associated with the study, including the original raw data and supporting data from replica experiments. The committee determined that Fig. 5D in the Diabetes article is correct and that “misrepresentation” occurred in the original Fig. 2F of the Human Molecular Genetics article. A corrigendum to replace Fig. 2F in the Human Molecular Genetics article was published in March 2015 (5).
According to the authors, the committee also concluded that duplication occurred between Fig. 3D and Fig. 5D of the Diabetes article (2,3). The committee determined that the “cleaved Casp3” panel in Fig. 3D is “incorrect” and that the “cleaved Caspase 3” panel in Fig. 5D is correct. At the recommendation of the Rector of the University of Bremen, the authors proposed to publish an erratum to correct “the wrongly placed western blot band.” This recommendation is also expressed in the Rector’s statement about the results of the university’s investigation (6), which states that the Rector “obliged Dr. Mädler to communicate the image duplications identified in the investigations to the publishers of the concerned journals and possibly publish Errata in consultation with the co-authors.”
On the basis of its review, however, ADA’s Panel on Ethical Scientific Programs (ESP) has concluded that the multiple confirmed duplications involving this article, one of which was introduced with the publication of the 2014 erratum (2), compromise the overall reliability of the data. Furthermore, the ESP has determined that such concerns regarding the reliability of the data cannot be sufficiently mitigated by publishing another erratum with another image; therefore, the Panel recommends to retract the article, and ADA has accepted this recommendation.
Diabetes is a member journal of the Committee on Publication Ethics (COPE), and ADA’s decision to accept the Panel’s recommendation to retract the article is in agreement with COPE’s guideline that journals should consider retracting an article when there is “clear evidence that the findings are unreliable, either as a result of misconduct (e.g., data fabrication) or honest error (e.g., miscalculation or experimental error)” (7).