Water intake and risk of type 2 diabetes: A systematic review and meta-analysis of observational studies

Background and aimsThe association of water intake with type 2 diabetes mellitus (T2DM) is still unclear. Therefore, the aim of this systematic review and meta-analysis was to synthesize the knowledge about the relationship between water intake and the risk of T2DM.MethodsWe conducted a systematic search in PubMed and Scopus up to June 2018 for observational studies. Risk ratios (RR)s and 95% confidence intervals (95% CI)s were calculated and fixed effects models were used.ResultsOverall, 6 studies were included in the meta-analyses. There was an inverse relationship between water intake and risk of T2DM (RR: 0.94; 95% CI: 0.91–0.97, P < 0.001) with low heterogeneity (I2 = 24%, P = 0.24).ConclusionOur findings indicated that the intake of water was correlated with reduced risk of type 2 diabetes in women and men. These results support the current recommendations of water intake as an inseparable part of a diet with the lowest risk of diabetes mellitus.     

Metformin and risk of cancer among patients with type 2 diabetes mellitus: A systematic review and meta-analysis

AimWe carried out this meta-analysis on all published studies to estimate the overall cancer risk of the use of metformin in T2DM patients.MethodsWe searched the PubMed, Embase and CNKI databases for all articles within a range of published years from 2007 to 2019 on the association between the use of metformin and cancer risk in T2DM patients. The odds ratio (OR) corresponding to the 95% confidence interval (95% CI) was used to assess the association using a random-effect meta-analysis.ResultsFinally, 67 studies met the inclusion criteria for this study, with 10,695,875 T2DM patients and 145,108 cancer cases. Overall, For T2DM patients of ever vs. never metformin users, there was statistical evidence of significantly decreased cancer risk was found to be associated with ever metformin users (OR = 0.70, 95% CI = 0.65–0.76). Considering T2DM may be a specific and independent risk factor for various forms of cancer, due to its particular metabolic characteristics of glucose intolerance and hyperinsulinemia, we performed a comparison to estimate the effects of metformin on cancer risk with other anti-diabetes medications (ADMs), our results found significantly decreased cancer risk to be associated with the use of metformin (OR = 0.80, 95% CI = 0.73–0.87).ConclusionOur meta-analysis indicated that metformin may be a independent protective factor for cancer risk in T2DM patients.     

Metformin is associated with reduced risk of pancreatic cancer in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

Aims

Recent epidemiological studies indicated that use of metformin might decrease the risk of various cancers among patients with type 2 diabetes mellitus (T2DM). However, its influence on pancreatic cancer was controversial. Therefore, we did a meta-analysis of currently available observational studies on the issue.

Methods

We did a PubMed and ISI Web of Science search for observational articles. The pooled relative risk (RR) was estimated using a random-effect model. Heterogeneity was evaluated using I² statistic. Subgroup analysis was performed to explore the source of heterogeneity and confirm the overall estimates. Publication bias was also examined.

Results

The analysis included 11 articles (13 studies) comprising 10 cohort studies and 3 case–control studies. Use of metformin was associated with a significant lower risk of pancreatic cancer [RR 0.63, 95% confidence internal (CI) 0.46–0.86, p = 0.003]. In a total 11 subgroup analyses, 5 provided the consistent result with pooled effect estimates of overall analysis. No publication bias was detected by Begg's (Z = −0.79, p = 0.428) and Egger's test (t = −0.92, p = 0.378).

Conclusions

From present observational studies, use of metformin appears to be associated with a reduced risk of pancreatic cancer in patients with T2DM. Further investigation is needed.     

Triglyceride-glucose index predicts independently type 2 diabetes mellitus risk: A systematic review and meta-analysis of cohort studies

ObjectiveOur objective was to perform a systematic review and meta-analysis of cohort studies evaluating the triglyceride-glucose (TyG) index as a tool for type 2 diabetes (T2D) prediction in adults and older adults.MethodsStudies were identified in PubMed, Cochrane, Scopus, and Lilacs. Studies with cohort design, which evaluated the T2D incidence through the hazard ratio (HR) or relative risk (RR) or odds ratio values were included. Were included both studies that evaluated the incidence of T2D from tertiles, quartiles, quintiles, or single TyG index values. First, a meta-analysis only for studies that reported data in HR values was performed. Additionally, given the different association measurements used, the number of T2D cases, non-T2D cases, and the total number of participants were extracted from exposed and non-exposed groups when available. Then the risk ratio was calculated. A meta-analysis using the inverse variance method and the random-effects model was performed. Heterogeneity was assessed by I² statistics and by inspecting funnel plots.ResultsThirteen cohort studies with a total of 70,380 subjects, both sexes, adults, and older adults were included in the meta-analysis. Ten studies showed a significant association of the TyG index with T2D risk through HR estimative (overall HR: 2.44, 95% CI: 2.17–2.76). After estimating RR for nine studies, we also observed a significant association of the TyG index with T2D risk (RR: 3.12, 95 CI: 2.31–4.21). For all analyses, high heterogeneity was verified by I² and visual inspection of funnel plots.ConclusionsTyG index has a positive and significant association with T2D risk, suggesting that the TyG index may become an applicable tool to identify subjects with T2D risk. However, due to the high heterogeneity observed in overall HR and RR analysis, more studies could be necessary to confirm these results.     

Association of type 2 diabetes mellitus and the risk of colorectal cancer: A meta-analysis and systematic review

AIM: To provide a quantitative assessment of the association between type 2 diabetes mellitus(T2DM)and the risk of colorectal cancer(CRC).METHODS: Systematic review was conducted thorough MEDLINE, EMBASE, Cochrane Library, andISI Web of knowledge databases till 31 st January 2014.This meta-analysis included the cohort studies that illustrated relative risk(RR) or odds ratio estimates with 95%CI for the predictive risk of CRC by T2 DM.Summary relative risks with 95%CI were analyzed by using an effects summary ratio model. Heterogeneity among studies was assessed by the Cochran's Q and I 2statistics.RESULTS: The meta analysis of 8 finally selected studies showed a positive correlation of T2 DM with the risk of CRC as depicted by effects summary RR of 1.21(95%CI: 1.02-1.42). Diabetic women showed greater risk of developing CRC as their effect summary RR of 1.22(95%CI: 1.01-49) with significant overall Z test at 5% level of significance was higher than the effect summary RR of 1.17(95%CI: 1.00-1.37) of men showing insignificant Z test. The effect summary RR of 1.19 with 95%CI of 1.07-1.33 indicate a positive relationship between DM and increased risk of CRC with significant heterogeneity(I 2 = 92% and P-value 0.05).CONCLUSION: Results from this systematic review and meta-analysis report that diabetic people have an increased risk of CRC as compared to non-diabetics.     

Cytokines in patients with type 2 diabetes and chronic periodontitis: A systematic review and meta-analysis

Individuals with type 2 diabetes mellitus (T2DM) and chronic periodontitis have significantly higher levels of interleukin-1 beta compared with systemically healthy individuals with chronic periodontitis. However, there was no significant difference in gingival crevicular levels of other cytokines between individuals with and without T2DM.     

The association between gestational diabetes mellitus and cancer in women: A systematic review and meta-analysis of observational studies

AimBoth type 1 and type 2 diabetes are associated with greater risk of a variety of cancers. However, the association between gestational diabetes mellitus (GDM) and risk of cancer has so far not been well addressed. This study aimed to summarize the epidemiological evidence of the association between GDM and subsequent risk of cancer.MethodsPubMed and Embase databases were searched for relevant studies, and a random-effects model was used to calculate the summary relative risks (RRs) along with the corresponding 95% confidence intervals (CIs).ResultsA total of 17 observational studies were selected, comprising 7 case–control and 10 cohort studies. Pooled effect estimates retrieved from these 17 studies showed that GDM was associated with an increased risk of breast cancer in Asia (pooled RR: 1.31, 95% CI: 1.01–1.70), but not in other regions, and also with thyroid cancer (RR: 1.28, 95% CI: 1.16–1.42), stomach cancer (RR: 1.43, 95% CI: 1.02–2.00) and liver cancer (RR: 1.27, 95% CI: 1.03–1.55). However, GDM was not associated with any increased risk of colon (RR: 1.41, 95% CI: 0.90–2.21), colorectal (RR: 1.16, 95% CI: 0.95–1.41), ovarian (RR: 1.14, 95% CI: 0.90–1.44), cervical (RR: 1.02, 95% CI: 0.81–1.29), pancreatic (RR: 3.49, 95% CI: 0.80–15.23), brain and nervous system (RR: 1.26, 95% CI: 0.80–1.97), blood (leukaemia, RR: 0.77, 95% CI: 0.45–1.30), endometrial (RR: 0.77, 95% CI: 0.20–2.98), skin (RR: 1.13, 95% CI: 0.81–1.59) or urological (RR: 0.98, 95% CI: 0.73–1.31) cancers.ConclusionGDM is associated with a greater risk of cancer in women, including breast, thyroid, stomach and liver cancers. However, further investigation is nonetheless warranted.     

Meat consumption and the risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

Aims/hypothesis  

Diet is thought to play an important role in the aetiology of type 2 diabetes. Previous studies have found positive associations between meat consumption and the risk of type 2 diabetes, but the results have been inconsistent. We conducted a systematic review and meta-analysis of cohort studies of meat consumption and type 2 diabetes risk.     

Prevalence of obstructive sleep apnea in patients with type 2 diabetes: A systematic review and meta-analysis

Obstructive sleep apnea (OSA) is highly prevalent among patients with diabetes, intensifying the complications of the disease. Various studies in Iran have reported different prevalence rates. This systematic review and meta-analysis was performed to determine OSA prevalence in patients with type 2 diabetes in Iran. In this study, we evaluated five articles published in Persian and English. The articles were searched using the keywords of obstructive sleep apnea, sleep disordered breathing, sleep apnea, OSA, diabetes mellitus and Iran and all possible combinations of these terms in national databases of Scientific Information Database (SID) and Magiran and international databases of Google Scholar, Web of Science, PubMed and Scopus with no time limit. Data were analyzed using the meta-analysis and random effects model. In addition, the heterogeneity between studies was assessed using I² statistic, and data analysis was performed in Stata version 11. In this study, five articles with a total sample size of 2360 were evaluated. According to the results, the prevalence of OSA in diabetic patients was reported to be 54.50% (95% Confidence Interval [CI]: 39.90–69.09). In addition, the results were indicative of a lower prevalence of OSA in men (63.26%; 95% CI: 43.26–83.26), compared to women (66.22%; 95% CI: 57.60–74.84). According to the results of the study, there was a high OSA prevalence in patients with type 2 diabetes. Therefore, it is crucial to recognize diabetic patients at risk of OSA to decrease the adverse effects of this condition.     

Thiazolidinedione use and cancer incidence in type 2 diabetes: A systematic review and meta-analysis

AimsEvidence suggests thiazolidinediones (TZDs) may modify the relationship between type 2 diabetes and cancer incidence. We aimed to summarize data from randomized controlled trials (RCTs) and observational studies to examine risk of overall and site-specific cancers with TZD use in individuals with type 2 diabetes.MethodsWe searched 12 key biomedical databases and seven grey literature sources up to June 2011, without language restrictions. We performed separate meta-analyses according to cancer site and study design, comparing ever-use to never-use of TZDs, and pioglitazone alone.ResultsThe search yielded 1338 unique citations; we included four RCT, seven cohort and nine nested case-control studies, contributing data from 2.5 million people. Estimates from observational studies suggested any TZD use was associated with a decreased risk of colorectal (pooled RR: 0.93, 95%CI 0.87–1.00, P = 0.04, I² = 30%), lung (pooled RR: 0.91, 95%CI 0.84–0.98, P = 0.02, heterogeneity (I²) = 35%) and breast (pooled RR: 0.89, 95%CI 0.81–0.98, P = 0.02, I² = 44%) cancer. Risk of overall cancer with TZD use was not significantly modified in RCTs (pooled RR: 0.92, 95%CI 0.79–1.07, P = 0.26, I² = 0%) or observational studies (pooled OR: 0.95, 95%CI 0.78–1.16, P = 0.63, I² = 70%). Pioglitazone use was, however, associated with a decreased risk of overall cancer (colorectal, lung, breast, prostate and renal sub-sites combined) in observational studies (pooled RR: 0.95, 95%CI 0.91–0.99, P = 0.009, I² = 0%).ConclusionsOur findings suggest that use of TZDs is associated with a modest but significantly decreased risk of lung, colorectal and breast cancers. Results were limited by the paucity of studies designed to answer our research question. Further evaluation of TZD use, cancer risk factors and potential confounders is required.     

Association between nut consumption and prostate cancer risk in adults: A systematic review and dose-response meta-analysis of observational studies

AimsData on the association between nut consumption and prostate cancer risk are conflicting. Therefore, this systematic review and dose-response meta-analysis aimed to summarize available findings from observational studies on the associations of nut intake with risk of total, advanced, non-advanced, and fatal prostate cancers.Data synthesisWe searched the online databases of PubMed, Scopus, and Web of Science as well as Google Scholar using appropriate keywords to identify eligible articles up to September 2022. In total, 11 articles with a total sample size of 287,786 participants and 32,213 cases of prostate cancer were included in the current systematic review and meta-analysis. By comparing the highest and lowest intake of total nuts, pooled relative risks (RRs) and 95% confidence intervals (95% CIs) for total, advanced, non-advanced, and fatal prostate cancers were 0.94 (95% CI: 0.85–1.04, P = 0.22), 1.10 (95% CI: 0.98–1.24, P = 0.12), 0.97 (95% CI: 0.85–1.11, P = 0.69), 0.97 (95% CI: 0.79–1.18, P = 0.73), respectively, which indicated non-significant inverse associations for total, non-advanced, and fatal prostate cancers and a non-significant positive association for advanced prostate cancer. In the dose-response analyses, we found no evidence of a linear or non-linear association between total nut intake and prostate cancer risk. Data on other types of nuts, including walnut, tree nuts, peanut, and peanut butter, were not sufficient for performing a meta-analysis.ConclusionWe found no significant association between nut intake and risk of total, advanced, non-advanced, and fatal prostate cancer. Further studies are required to confirm our findings.Prospero registration codeCRD42022347094.Ethical approvalNot required.     

Breastfeeding and the maternal risk of type 2 diabetes: A systematic review and dose–response meta-analysis of cohort studies

Background and aimsBreastfeeding has been associated with reduced risk of maternal type 2 diabetes in some cohort studies, but the evidence from published studies have differed with regard to the strength of the association. To clarify this association we conducted a systematic review and dose–response meta-analysis of breastfeeding and maternal risk of type 2 diabetes.Methods and resultsWe conducted a systematic review and dose–response meta-analysis of prospective studies of breastfeeding and maternal risk of type 2 diabetes. We searched the PubMed, Embase and Ovid databases up to September 19th 2013. Summary relative risks were estimated using a random effects model. Six cohort studies including 10,842 cases among 273,961 participants were included in the meta-analysis. The summary RR for the highest duration of breastfeeding vs. the lowest was 0.68 (95% CI: 0.57–0.82, I² = 75%, p_{heterogeneity} = 0.001, n = 6). The summary RR for a three month increase in the duration of breastfeeding per child was 0.89 (95% CI: 0.77–1.04, I² = 93%, p_{heterogeneity} < 0.0001, n = 3) and the summary RR for a one year increase in the total duration of breastfeeding was 0.91 (95% CI: 0.86–0.96, I² = 81%, p_{heterogeneity} = 0.001, n = 4). There was little difference in the summary estimates whether or not BMI had been adjusted for. The inverse associations appeared to be nonlinear, p_nonlinearity < 0.0001 for both analyses, and in both analyses the reduction in risk was steeper when increasing breastfeeding from low levels.ConclusionThis meta-analysis suggests that there is a statistically significant inverse association between breastfeeding and maternal risk of type 2 diabetes.