Studies on the association between serum magnesium level and prediabetes yielded inconsistent results. Therefore, the present meta-analysis was designed to examine the association between serum magnesium levels and prediabetes. Online databases including PubMed, Embase, Scopus and Google Scholar were searched up to October, 2020. A total of 10 studies that reported mean and standard deviation (SD) of magnesium levels in prediabetes and healthy control group were identified. Random effects models were used to pool weighted mean differences (WMDs) of serum magnesium levels. Pooled-analysis showed that subjects with prediabetes had significantly lower serum magnesium levels compared with healthy controls (WMD =  − 0.07 mmol/L; 95% CI − 0.09, − 0.05 mmol/L, P < 0.001). A significant heterogeneity observed across included studies (I2 = 95.6%, P < 0.001). However, different subgroup analysis did not detect the potential source of observed heterogeneity. Withdrawal of each individual study had no effect on the overall results. The present meta-analysis showed that circulating magnesium levels in people with prediabetes were significantly lower than healthy controls, confirming that magnesium deficiency may play a role in development and progression of prediabetes. Further studies with larger sample size and robust design are warranted to confirm present results.

ObjectiveProspective cohort studies on coffee, tea and caffeine in relation to the risk of rheumatoid arthritis (RA) have shown conflicting results. The aim of this study was to conduct a dose–response meta-analysis of cohort studies on the association between dietary caffeine, different types of coffee and tea consumption and the risk of RA.MethodsPubMed/Medline, Scopus and EMBASE were searched up to July 2021 to identify relevant studies that had considered different types of coffee (caffeinated or decaffeinated), tea or caffeine exposure with RA as the main, or one of the, outcome(s). Two authors independently screened 742 publications. Finally, five prospective cohort studies were included in our meta-analysis. Pooled relative risks (RRs) were calculated by using a fixed-effects model. We also performed linear and non-linear dose-response analyses to examine the dose-response relations.ResultsComparing extreme categories, we found a positive, significant association between coffee (RR: 1.30; 95% CI: 1.04–1.62; I2 = 0%, n = 5) and decaffeinated coffee (RR: 1.89; 95% CI: 1.35–2.65; I2 = 38.1%, n =3) consumption and risk of RA. One additional cup of coffee consumed per day was associated with an increased risk of RA by 6% (95% CI: 1.02–1.10; I2 = 0%). This increase in the risk of RA for one cup/d of decaffeinated coffee was 11% (95% CI: 1.05–1.18; I2 = 38). No significant association was observed between caffeinated coffee, tea or caffeine intake and the risk of RA.ConclusionWe found that a higher intake of coffee and decaffeinated coffee was associated with increased risk of RA. No significant association between caffeinated coffee, tea or caffeine intake and the risk of RA was observed.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=227665, identifier: CRD42021227665.

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A prominent issue for patients with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is obesity. Some reports claim that obese patients with acute respiratory distress syndrome have better outcomes. This inverse relationship has been termed the obesity paradox and is not yet understood in patients with coronavirus disease 2019 (COVID-19) hospitalized in the intensive care unit (ICU). The aim of this study was to investigate the obesity paradox in patients with COVID-19 admitted to the ICU. In this retrospective observational study, 5230 patients with COVID-19, admitted to the ICU between June 1, 2020, and January 10, 2021, were analyzed. Body mass index (BMI) was calculated according to the World Health Organization classification, and patients were categorized as underweight, normal, overweight, or obese for statistical analysis. A Kaplan-Meier survival analysis, Cox regression model, and dose-response relationship between BMI level and ICU length of stay (LOS) and connection to the ventilator survival were conducted. Of the 5230 patients studied, 3233 (62%) had nonobese BMIs, and 2997 (38%) were obese. We found no significant difference in mortality between obese and nonobese patients with COVID-19, where 1699 patients (31%) survived. However, there were significant differences in BMI level for ICU LOS and ventilation duration (P < 0.05, P < 0.03). In multivariable Cox regression, significant differences were observed in ICU LOS and ventilation duration of patients between obese and nonobese patients (P < 0.001, P < 0.005). There was no association between BMI and survival among patients with LOS in the ICU LOS or connection to a ventilator. However, obese patients with COVID-19 require more care than nonobese patients because of additional comorbidities, higher inflammation, and a weaker immune system.