Reviewer ’s report  
 
Title: The effect of a diabetes prevention program on dietary quality in women with previous 
gestational diabetes  
 
Version: 0 Date: 08 Apr 2019  
 
Reviewer: Rebecca Dennison  
 
Reviewer's report:  
 
This is a secondary analysis of the MAGDA trial, a diabetes prevention programme in women 
with a history of gestational diabetes including diet and physical activity counselling. This 
analysis looks at self -reported diet (through the Australian Recommended  Food Score, ARFS) 
before and after the intervention, and in control versus intervention groups. Overall, this is an 
interesting paper to read with relevance to dietary intervention in post -GDM and, probably, non -
GDM women. Follow -up is complete, the table s are detailed and the methods are clearly 
presented.  
However, there are important limitations that I feel should be explained more thoroughly, and the 
conclusions should be placed in context of these limitations. I have suggested several points 
below and  hope that the authors agree that these could improve the accuracy of readers' 
understanding.  
In this paper, the PPS is referred to as the main (most interesting) analysis. The authors should 
present the differences between this and the ITT group (such as the number within each arm in 
the PPS and whether they are similar to the ITT group of that arm), and indicate the limitations 
of per protocol analyses. Briefly comparing Tables 3 and 4, there are some differences at 
baseline that are larger than the ch ange over time (e.g. fish), which suggests not always. 
Furthermore, more space could be given to describe the results (including intervention 
attendance, Table 5) and the findings of the primary trial analysis summarised much more 
briefly.  
In the discussion, the authors conclude that "This demonstrates the importance of participants' 
engagement in yielding intervention outcomes." (lines 313 -314) and "We have also shown in the 
current study that dietary improvements were related to attendance ." (367 -368). I think that the 
findings suggest, rather than demonstrate, the importance of engagement/attendance and that this 
should be presented more cautiously and explored in the discussion. Another possibility is that 
people who are more likely to ch ange their diet had better intervention attendance. [Did the 
authors come to this conclusion (i) because a significant effect was found in the PPS but not ITT 
and/or (ii) because of the numbers attending each session? In response, (i) in addition to my 
comments above, although all participants in the PPS meet the minimum intervention exposure, 
only a third of those excluded were for reasons related to attendance; minimum intervention 
exposure has a low cut off of 1/5 group and the individual session. (ii) T he last two sessions 
didn't appear to focus on dietary changes that could be assessed using the ARFS therefore low 
attendance here cannot be used for comparison.]  
Lines 213 -222: double check numbers in the reasons for exclusion from the PPS (I found that the 
reasons given in lines 216 -221 summed to n=238, whereas the difference between the ITT (573) 
and PPS (331) is n=242).  
Lines 275 -276: "The ARFS sub -category analysis for nuts and legumes was significantly 
improved (p=0.04)." For the intervention group,  Table 3 says baseline score: 1.82, 12 months: 
1.61, difference: -0.20. Is this decreased score definitely an improvement?  
In lines 364 -373, the authors describe limitations of their study; these relate to low attendance at 
the intervention sessions and the relatively low metabolic risk of the participants. Other 
limitations should be considered: for example, error and bias in the self -reported FFQ (has this 
instrument been validated? This is mitigated by analysing change in outcome), multiple 
hypothesis testing without adjustment for multiplicity, and that this analysis was not part of the 
original proposal (even though the PPS was a priori).  
 
Minor suggestions  
- Line 29: give total possible ARFS.  
 
- Lines 56 -59: more recent studies reporting incidence in Australian populations (this would be 
more relevant demographically and in defining GDM/T2D) or a synthesised estimate could 
be reported instead. For example, Lee et al. 2007 (DOI: 10.2337/dc06 -1816) or Ingram et al. 
2017 (DOI: 10.1111/ajo.12514)  
 
- Lines 8 8-91: can you clarify these sentences? (What do 'qualitative dietary adherence' and 'a 
better reflection on the uptake of dietary advice' mean? Are these two sentences saying the 
same thing?)  
 
- Line 132: indicate that Table 1 here refers to the citation, n ot the present manuscript.  
 
- Description of the intervention: please add when the intervention was delivered in relation to 
pregnancy (or when was baseline) and the content of the individual session.  
 
- Line 229: be consistent with p<0.05 or p≤0.05 through out (e.g. table footnotes).  
 
- Line 232: define GGT -DPP.  
 
 
- Refer to Table 1 in the text.  
 
- Lines 342 -344: Indicate that this is in the MAGDA participants compared to the survey 
above, and which numbers quoted refer to which study.  
 
- Table 1: is this table m issing significance values for Quality of Life Score to FPG?  
 
- Tables 3 and 4: consider rewording "Difference in time" - e.g. change or change over time, 
and adding n's.  
 
- There are also several cases where sentences should be written out in full (not not es) and 
typos corrected.  
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
Are you able to assess any statistics in t he manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of  written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
  
Declaration of competing interests  
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