Background: COVID-19 might be a risk factor for various chronic diseases. However, the association between COVID-19 and the risk of incident diabetes remains unclear. We aimed to meta-analyze evidence on the relative risk of incident diabetes in patients with COVID-19. Methods: In this systematic review and meta-analysis, the Embase, PubMed, CENTRAL, and Web of Science databases were searched from December 2019 to June 8, 2022. We included cohort studies that provided data on the number, proportion, or relative risk of diabetes after confirming the COVID-19 diagnosis. Two reviewers independently screened studies for eligibility, extracted data, and assessed risk of bias. We used a random-effects meta-analysis to pool the relative risk with corresponding 95 % confidence intervals. Prespecified subgroup and meta-regression analyses were conducted to explore the potential influencing factors. We converted the relative risk to the absolute risk difference to present the evidence. This study was registered in advance (PROSPERO CRD42022337841). Main findings: Ten articles involving 11 retrospective cohorts with a total of 47.1 million participants proved eligible. We found a 64 % greater risk (RR = 1.64, 95%CI: 1.51 to 1.79) of diabetes in patients with COVID-19 compared with non-COVID-19 controls, which could increase the number of diabetes events by 701 (558 more to 865 more) per 10,000 persons. We detected significant subgroup effects for type of diabetes and sex. Type 2 diabetes has a higher relative risk than type 1. Moreover, men may be at a higher risk of overall diabetes than women. Sensitivity analysis confirmed the robustness of the results. No evidence was found for publication bias. Conclusions: COVID-19 is strongly associated with the risk of incident diabetes, including both type 1 and type 2 diabetes. We should be aware of the risk of developing diabetes after COVID-19 and prepare for the associated health problems, given the large and growing number of people infected with COVID-19. However, the body of evidence still needs to be strengthened.

Background Several clinical trials investigated the effects of enteral lactoferrin supplementation on the prevention of sepsis and necrotizing enterocolitis (NEC) in preterm infants, but the efficacy and safety remain disputed. Therefore, we systematically evaluated the effect of enteral lactoferrin supplementation in preterm infants through a meta-analysis with trial sequential analysis (TSA). Methods We searched six databases to identify randomized controlled trials (RCTs) that evaluated the effects of lactoferrin supplementation compared with placebo or no intervention in preterm infants. RevMan version 5.3 software was used to estimate pooled relative risks (RRs) with the random-effects model. TSA, subgroup analyses, and meta-regression analyses were also performed. Results Nine RCTs with 3515 samples were included. With low to moderate quality of evidence, compared with placebo, enteral lactoferrin supplementation did not significantly decrease the incidences of late-onset sepsis (RR = 0.63, 95% CI: 0.38 to 1.02,P= 0.06), NEC stage II or III (RR = 0.68, 95% CI: 0.30 to 1.52,P= 0.35), all-cause mortality (RR = 0.89, 95% CI: 0.51 to 1.57,P= 0.69), bronchopulmonary dysplasia (RR = 1.01, 95% CI: 0.90 to 1.13,P= 0.92), retinopathy of prematurity (RR = 0.80, 95% CI: 0.49 to 1.32,P= 0.38), invasive fungal infection (RR = 0.27, 95% CI: 0.02 to 3.94,P= 0.34), intraventricular hemorrhage (RR = 1.40, 95% CI: 0.39 to 5.08,P= 0.61), and urinary tract infection (RR = 0.35, 95% CI: 0.11 to 1.06,P= 0.06). Subgroup analysis revealed that lactoferrin significantly reduced the incidence of sepsis in infants with a birth weight below 1500 g (RR = 0.43, 95% CI: 0.22 to 0.84,P= 0.01). TSAs of the primary outcomes showed that the evidence is insufficient and further data is required. Conclusions Limited evidence suggested that enteral lactoferrin supplementation was associated with a reduction of late-onset sepsis in infants with a birth weight below 1500g, however, did not decrease the incidence of NEC stage II or III, all-cause mortality, and other adverse events in preterm infants. The present evidence was insufficient to inform clinical practice.