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Background This meta-analysis was first conducted to evaluate the efficacy and safety of transplantation of mesenchymal stem cells in the treatment of type 1 and type 2 diabetes mellitus (T1DM and T2DM). Methods We systematically searched PubMed, ScienceDirect, Google Scholar, CNKI, EMBASE, Web of Science, MEDLINE, and the Cochrane Library for studies published from the establishment of the databases to November 2020. Two researchers independently screened the identified studies, based on inclusion and exclusion criteria. The combined standard mean difference (SMD) and 95% confidence interval (CI) of data from the included studies were calculated using fixed- or random-effects models. Results We included 10 studies in our meta-analysis (4 studies on T1DM and 6 on T2DM, with 239 participants) to examine the efficacy of mesenchymal stem cells (MSCs) therapy in the treatment of diabetes mellitus. According to the pooled estimates, the glycated hemoglobin (HbA1c) level of the MSC-treated group was significantly lower than it was at baseline (mean difference (MD) = −1.51, 95% CI −2.42 to −0.60, P = 0.001). The fasting C-peptide level of the MSC-treated group with T1DM was higher than that of the control group (SMD = 0.89, 95% CI 0.36 to 1.42, P = 0.001), and their insulin requirement was significantly lower than it was at baseline (SMD = −1.14, 95% CI −1.52 to −0.77, P < 0.00001). Conclusion Transplantation of mesenchymal stem cells has beneficial effects on diabetes mellitus, especially T1DM, and no obvious adverse reactions.

This meta-analysis systematically evaluated the effects of water improvement and defluoridation on fluorosis-endemic areas in North and South China. The study used PubMed, Embase, China National Knowledge Infrastructure, and Wanfang to retrieve relevant research studies published between January 2000 and October 2019. The data included water fluoride levels, dental fluorosis prevalence in children 8–15 years of age, urinary fluoride levels in children and adults, and skeletal fluorosis prevalence in adults. Fixed-effects and random-effects models were used in the meta-analysis. A total of 17 research articles met the inclusion criteria and had an average water improvement period of 15.8 years. With water improvement, water fluoride levels decreased from 2.72 mg/L to 0.54 mg/L (95% confidence intervals: −2.75, −1.58), which was below the standard for drinking water (1.5 mg/L). Additionally, after water improvement, the prevalence of dental fluorosis decreased from 54.5% to 36.2% (95% confidence intervals: 0.12, 0.31) in children, and the prevalence of skeletal fluorosis decreased from 13.7% to 4.2% (95% confidence intervals: 0.16, 0.40) in adults. Urinary fluoride levels decreased from 3.06 mg/L to 1.70 mg/L (OR = −2.03, 95% confidence intervals: −2.77, −1.30) in children and from 2.29 mg/L to 1.72 mg/L (OR = −0.57, 95% confidence intervals: 0.65, −0.49) in adults. The results showed that the prevalence of dental fluorosis and skeletal fluorosis and urinary fluoride levels were significantly reduced by water improvement. This study findings revealed that the effects of water improvement and defluoridation were greater in South China than in North China, and it is obviously related to the time of water improvement and reducing fluoride.