Review Reports

Round 1

Reviewer 1 Report

In this preliminary study 26 adults with prediabetes were given a supplement that contained Portulaca oleracea and titrated Cistus creticus along with certain other minerals and viatmins for 3 months, and various biochemical parameters (some of which related to glucose tolerance) were tested at the beginning and end of the study. There was a small drop in fasting glucose concentrations along with a proportionally larger drop in fasting insulin concentration, suggesting an increase in insulin sensitivity. Whilst this may relate to the plant-based extracts, it is not clear from the results as it could also relate to the additional contents of the supplement, or changes in diet or exercise (that were not controlled for). Whilst this is clearly a preliminary study, it is a shame that these other potential confounders were not controlled for (e.g. by having a control group that took a supplement containing just the minerals and vitamins, doing simple dietary and exercise assessments) as it limits the overall value of the study.

Specific Comments

1. Lines 42-44. Please qualify this statement as diabetes is not always accompanied by hyperinsulinemia (e.g. type 1 diabetes) and hypertryglyceridemia.

2. Lines 81-82. Please provide a reference for this statement, as the following sentences deal with vitamin and mineral supplementation, rather than showing that individuals with hyperglycemia often have altered levels of essential minerals and vitamins.

3. Lines 103-106. Please give details about how the extracts were produced.

4. Line 114. Why were 26 people studied? Also, how were they recruited (e.g. from a clinic, responding to an advert)?

5. Line 124. Please provide more details about the instructions for diet and exercise, as these factors are potential confounders for the study.

6. Line 146. Was insulin really measured by colorimetry? Was the sample for glucose measurement not collected into fluroride oxalate (and so plasma glucose was measured, not serum which could have been affected by red cell glycolysis)?

7. Lines 151-152. Was HOMA IR calculated using the original formula or the more modern computer algorithm?

8. The Discussion section barely mentions the results of this study, and does not put them into context. I think that it needs to be substantially rewritten.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Thank you for the opportunity to review the manuscript. 

Should change Diabetes Mellitus (DM) to Type 2 Diabetes Mellitus (T2DM), which can be used through the paper. As this study mainly pertains to T2DM, whereas DM can be confused with type 1 diabetes mellitus as well. 

Line 63 - spelling of type 2 diabetes is wrong. Also should mention type 2 diabetes mellitus (T2DM). 

Either use FPG or FBG. Seems like both have been used interchangeably. 

Line 116 - Cushing's syndrome

 

Though the study is done fairly, but has major limitations:

- lack of control group

- small sample size

- short duration of intervention

- minimal change in parameters from baseline, which is an expected response to lifestyle modifications

-  it is difficult to justify these changes are due to the dietary supplements itself

-  would suggest to at least have a control group with similar lifestyle intervention

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

This revised manuscript is a considerable improvement on the previous version, for which the authors should take credit.

Only very minor edits are required to the English language used in the manuscript.

Reviewer 2 Report

Thanks for revising the manuscript.