Fig. 1.

Diagram flow illustrating the literature search and selection. ^aAlthough one of the studies included in a systematic review by Hariyanto et al. [6] was not included in the systematic review by Kow et al. [7], the study only pooled unadjusted rather than adjusted estimates; thus we decided to exclude the study by Hariyanto et al. [6] and assessed the non-duplicate study separately. CENTRAL, Cochrane Central Register of Controlled Trials; CINAHL, Cumulative Index to Nursing and Allied Health Literature. COVID-19, coronavirus disease 2019; SSRN, Social Science Research Network; T2DM, type 2 diabetes mellitus; WHO, World Health Organization COVID-19 Research Database