A Pilot Study of the Effect of Evening Almond Butter Consumption on Overnight and Fasting Interstitial Glucose

Round 1

Reviewer 1 Report

Thanks for addressing my comments. 

Author Response

Thank you very much.

Reviewer 2 Report

Goal of study:  Pilot study to determine the acute effect of evening almond butter consumption on overnight and fasting interstitial glucose

The manuscript was overall very clearly written.  The description of the study design was complete and detailed.  Alternatives and more specific recommendations we can give our patients to prevent morning hyperglycemia would be very helpful.  However, the endpoints chosen for this study seems too large for scope of study. 

General comments:

1)     The authors did elaborate on current evidence of nuts and almonds on markers of diabetes control. What was the rationale of using almond butter vs using nuts or almonds?  What additional information will this study help provide? 

2)     It is clear that this is a pilot study so one would not necessarily expect that any significant differences would be found in the primary and secondary endpoints chosen.  Perhaps different endpoints might be more appropriate - it would be helpful to clarify other outcomes that the authors anticipate would aid in conducting a larger trial, i.e. tolerance of almond butter, etc. 

3)     Limitations of the study are described. The manuscript states that the pilot study “provides insights that may assist in the planning of future studies…”  What are these insights from the pilot study that you would continue to a larger study? 

 Specific comments:

1)     Table 1 described in text so Table not necessary for small sample size.

2)     In Table 3, untis can probably be listed in 1^st column so only numbers can be listed in other columns.  This could help make table less crowded.  It would also help to have Range in one line rather than going into next line (maybe Table can be presented in landscape mode). 

3)     In Figure 4, Panel C appears redundant with Figure 3.  Panel C could probably be taken out so sizing of Panel A and Panel B could be similar. 

4)     Lines 278-281could be one sentence versus three separate sentences.

Author Response

Reviewer 2

Comments and Suggestions for Authors

Goal of study:  Pilot study to determine the acute effect of evening almond butter consumption on overnight and fasting interstitial glucose

The manuscript was overall very clearly written.  The description of the study design was complete and detailed.  Alternatives and more specific recommendations we can give our patients to prevent morning hyperglycemia would be very helpful.  However, the endpoints chosen for this study seems too large for scope of study. 

Thank you for your thoughtful comments. We feel the edits we made as a result have helped to improve the reporting of our study. 

General comments:

• The authors did elaborate on current evidence of nuts and almonds on markers of diabetes control. What was the rationale of using almond butter vs using nuts or almonds?  What additional information will this study help provide? 

 

Thanks for this question. The rationale is based on existing literature showing the impact of nuts, particularly almonds, on markers of glycemic control (Introduction lines 62-65).  

We selected almond butter due to previous anecdotal clinical work indicating this was a highly palatable, acceptable snack.

 

• It is clear that this is a pilot study so one would not necessarily expect that any significant differences would be found in the primary and secondary endpoints chosen.  Perhaps different endpoints might be more appropriate - it would be helpful to clarify other outcomes that the authors anticipate would aid in conducting a larger trial, i.e. tolerance of almond butter, etc. 

 

Thank you for this suggestion- we have added this to the discussion in lines 574-575 and added a note on compliance to the results section in line 198.

 

• Limitations of the study are described. The manuscript states that the pilot study “provides insights that may assist in the planning of future studies…”  What are these insights from the pilot study that you would continue to a larger study? 

 

Thank you for this question. We have added more information to the Discussion in lines 692-695.

 Specific comments:

• Table 1 described in text so Table not necessary for small sample size.

Thank you for this comment. We prefer to keep the table, but reduced the description in the text to avoid duplication of data.

 

• In Table 3, units can probably be listed in 1^stcolumn so only numbers can be listed in other columns.  This could help make table less crowded.  It would also help to have Range in one line rather than going into next line (maybe Table can be presented in landscape mode). 

Thank you, we have made this edit.

3)     In Figure 4, Panel C appears redundant with Figure 3.  Panel C could probably be taken out so sizing of Panel A and Panel B could be similar. 

Thank you for this comment. We have removed Panel C.

 

• Lines 278-281could be one sentence versus three separate sentences.

 

Thank you for your comment – we have edited the sentences.

Reviewer 3 Report

In the presented manuscript, the authors discuss the effect of almond butter consumption on overnight and fasting interstitial glucose in diabetic individuals. The authors further discuss the implication of their work with the Dawn Phenomenon. The results obtained, while not groundbreaking represent the finding of a pilot study that may be of great use for others thinking about designing studies related to dietary intervention.

 

Major:

Improvements on the curation of the data for a cleaner presentation may help point out the specific glucose values that were obtained during this study.

 

Lines:

Methods:

81- The authors introduce the study design and explain, what seems to be, the usage of the individuals tested as their own controls. I think this is a great approach. A constrain that arises is the lack of a period in between switching treatments. I believe this is critical to be discussed after presenting the findings, as other studies have suggested when designing these interventions (10.3390/nu11122862, 10.3389/fnut.2020.00079). Along, I would suggest the statement starting on line 82 be removed from their manuscript. 

 

Minor:

The discussion of this manuscript will greatly benefit from the addition of further discussion on existing nut or almond consumption and glycemic control. As well, of they may want to consider the addition of combined therapy, including drug and a nut snack. This is mentioned, as the individuals included in this study were using oral drugs already.

As well, suggestions for potential future study design or approaches may be included in the concluding part of this manuscript.

 

Lines:

Introduction:

68- The authors mention an “acute effect” on almond butter consumption, though their work considered consumption of ~32 gr, which seems to be within the limits of a standard serving size for different brands of almond butter, including the one used for this study. I would consider this when referring to the dosage of almond butter used for this study.

Author Response

Reviewer 3

Comments and Suggestions for Authors

In the presented manuscript, the authors discuss the effect of almond butter consumption on overnight and fasting interstitial glucose in diabetic individuals. The authors further discuss the implication of their work with the Dawn Phenomenon. The results obtained, while not groundbreaking represent the finding of a pilot study that may be of great use for others thinking about designing studies related to dietary intervention.

 

Thank you for your thoughtful comments. We feel the edits we made as a result have helped to improve the reporting of our study. 

 

Major:

Improvements on the curation of the data for a cleaner presentation may help point out the specific glucose values that were obtained during this study.

 

Lines:

Methods:

81- The authors introduce the study design and explain, what seems to be, the usage of the individuals tested as their own controls. I think this is a great approach. A constrain that arises is the lack of a period in between switching treatments. I believe this is critical to be discussed after presenting the findings, as other studies have suggested when designing these interventions (10.3390/nu11122862, 10.3389/fnut.2020.00079). Along, I would suggest the statement starting on line 82 be removed from their manuscript. 

 

Thank you for your comment. The statement on line 82 is recommended by the CONSORT guidelines for crossover studies since we expect carryover effects to be negligible or non-existent. We addressed the lack of potential for carryover effect in the discussion.

 

Minor:

The discussion of this manuscript will greatly benefit from the addition of further discussion on existing nut or almond consumption and glycemic control. As well, of they may want to consider the addition of combined therapy, including drug and a nut snack. This is mentioned, as the individuals included in this study were using oral drugs already.

As well, suggestions for potential future study design or approaches may be included in the concluding part of this manuscript.

 

Thank you for your comment. We have added a statement to the discussion in lines 617-622 to make this point. We addressed current intake in lines 696-701.

 

Lines:

Introduction:

68- The authors mention an “acute effect” on almond butter consumption, though their work considered consumption of ~32 gr, which seems to be within the limits of a standard serving size for different brands of almond butter, including the one used for this study. I would consider this when referring to the dosage of almond butter used for this study.

 

Thank you for your comment. Nuts and nut butters are calorically dense and therefore portion control is important for weight management, especially in a population with type 2 diabetes where weight can impact glycemic control. A recent systematic review found no association between dose of nuts and glycemic control where the dose ranged from 20 g/d to 113 g/d. We have added details on this to the discussion in lines 668-673.

Round 2

Reviewer 2 Report

Thank you for your responses.  Looking forward to the larger study. 

Reviewer 3 Report

I appreciate the modification provided by the authors and their rationale used in their responses.