Study Exclusion reasons Remarks Reference(s)
Fadini, 2020 case control no control group Each diabetic patient with COVID19 was matched with 200 controls with diabetes at the last observation in 2018 or 100 controls with diabetes hospitalized for any other reasons in 2018 or 5 diabetic patients hospitalized for pneumonia in 2018.

Fadini GP Diabetes Obes Metab 2020 Oct;22(10):1946-1950. 10.1111/dom.14097

 
Strollo, 2021 observational study no clinically relevant endpoint

Strollo R Diabetes Research and Clinical Practice 10.1016/j.diabres.2020.108444