Maternal Chromium Levels in Gestational Diabetes: Systematic Review and Meta-Analysis

The topic of maternal Chromium (Cr) levels in Gestational Diabetes Mellitus (GDM) has remained controversial; some studies have found lower levels of Cr in GDM population, whereas others found no significant changes in Cr status in GDM. Therefore, this systematic review and meta-analysis was aimed at qualitatively and quantitatively synthesizing past studies to find the relationship of maternal Cr levels with GDM. The study protocol was registered at International prospective register for systematic reviews (PROSPERO) (ID CRD42021272979). Strict adherence to the Preferred Reporting Items for Systematic review and Meta-analysis checklist, 2009 was followed during the entire study. Random-effect model for calculation of distribution of true effect sizes was used for the meta-analysis with a confidence interval (CI) of 95%. The pooled Standard Mean Difference of control and GDM groups were compared using Z statistics with a P value of <.05 as significant. Six studies were included for the systematic review and four studies entered meta-analysis. The test of overall effect revealed that the pooled Cr values did not differ significantly between controls and GDM group (Z = 1.52, P =0.13). Heterogeneity between the studies was high (I² = 97%). A subgroup analysis revealed that results varied as per place of study, trimester of pregnancy, and Cr estimation technique. Results from meta regression analysis revealed that sample size of individual studies (Q = 0.003, P =0.67) and year of publication of studies (Q = 0.22, P =.48) had no significant effect on the overall Standard Mean Difference. Factors such as ethnicity, lack of history of infection, and diet history can influence the results of this study.