While the main study objective has been stated as identifying the role of COVID-19 in new-onset of diabetes, the findings are not in line with this objective.

• The study main objective is to clarify whether COVID-19 induces new-onset diabetes or unmasks previously undiagnosed diabetes. However, the information provided in the text and table, demonstrated the risk of severe outcome in those with known diabetes vs. those with no history of diabetes. This is main flaw of the study.

• The study methodology is not clear. It’s not conclusive that the manuscript tried to simulate a systematic review or another type of review article?

• Please clarify the baseline for comparison when reporting the ORs in the following phrases:

• For the composite outcome, the odds ratio (OR) in patients with new-onset diabetes (5.47) was higher than the OR in those with known diabetes (2.61).

• Please clarify whether the authors had the access to the primary data of the included papers?

• Please clarify did the authors calculated the reported ORs as well as HRs or these estimations had been already stated in the included papers?

• If the authors calculated the aforementioned parameters, please explain its method.

• Page 3, lines 22-31. I don’t think that only reporting the proportion of those with previously undiagnosed diabetes could help to obtain the study objective.

• The conclusion is not relevant to the study main question.

See attached document also

I have no more comment.