|Year : 2018 | Volume
| Issue : 10 | Page : 644-647
Diabetes mellitus might be a protective factor of glioma
Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China
|Date of Web Publication||24-Sep-2018|
Putuo Hospital, Shanghai University of TCM, No. 164 Lanxi Road, Shanghai 200062
Source of Support: None, Conflict of Interest: None
Aims: Several studies suggested that diabetes mellitus (DM) was associated with the risk of glioma. However, other studies did not confirm the result. Therefore, I conducted this meta-analysis.
Materials and Methods: I retrieved the PubMed, Embase, and Web of Science database, by adopting keywords “glioma,” and “diabetes,” “DM.” The strength of the associations between DM and the risk of glioma was measured by odds ratios (ORs) with 95% confidence intervals (95% CIs).
Results: Ten relevant studies were identified in the final analysis. A statistically significant association between DM and glioma risk was fond (OR = 0.84; 95% CI, 0.73–0.97; P = 0.02). In the subgroup analysis of age group, young population with DM showed decreased glioma risk (OR = 0.83; 95% CI, 0.70–0.98; P = 0.02), whereas old population with DM did not show a significant association (OR = 0.87; 95% CI, 0.65–1.16; P = 0.34). In the subgroup analysis of gender, male patients with DM showed decreased glioma risk (OR = 0.82; 95% CI, 0.68–0.99; P = 0.04), whereas female population with DM did not show a significant association (OR = 0.93; 95% CI, 0.70–1.24; P = 0.63).
Conclusions: This meta-analysis suggested that DM may be associated with the reduced glioma risk.
Keywords: Association, diabetes mellitus, glioma, meta-analysis
|How to cite this article:|
Ni TT. Diabetes mellitus might be a protective factor of glioma. J Can Res Ther 2018;14, Suppl S3:644-7
| > Introduction|| |
Diabetes mellitus (DM) is a common chronic disease with tremendous impact on health worldwide. DM is the seventh leading cause of mortality, and is increasing in prevalence. Epidemiologic study suggests that people with diabetes are at significantly higher risk for many forms of cancer and greater cancer mortality. For example, Michels et al. suggested that women with type 2 diabetes may have a slightly increased risk of breast cancer. Hu et al. found that diabetes is associated with an increased risk of colorectal cancer in women. Friberg et al. indicated that DM was associated with a 2-fold increased risk, and combination of DM with obesity and low physical activity was associated with a further increased risk for endometrial cancer. Wang et al. found recent-onset diabetes may be a complication or an early marker of pancreatic cancer.
Several studies suggested that DM was associated with the risk of glioma. However, other studies did not confirm the result.,,,,,,,,, Therefore, to derive a more precise estimation of the association between DM and glioma risk, I conducted this meta-analysis.
| > Materials and Methods|| |
I retrieved the PubMed, Embase, and Web of Science database, by adopting keywords “glioma,” and “diabetes,” “DM.” I also conducted a hand retrieve of the references of the original articles or reviews on this issue for additional studies. All the eligible studies were restricted to humans. I will enroll the reports with largest sample size when more than one reports published the same data or data subsets.
Inclusion and exclusion criteria
Reports were enrolled referring to the following criteria: (a) Reports that assessed the association between DM and glioma risk, (b) case–control study or cohort study. Besides, I will exclude these studies when they were: (a) Case reports, case-only study or reviews, (b) animal studies, and (c) duplicated publications.
Data extraction and quality assessment
The following details should be concerned: The name of the first author, the year of publication, the mean age of each study, the male number of study, the case number of each study, and the covariants. I compared the data.
The Newcastle–Ottawa Scale (NOS) was used to evaluate the methodological quality, which scored studies by the selection of the study groups, the comparability of the groups, and the ascertainment of the outcome of interest. I considered a study awarded 0–3, 4–6, or 7–9 as a low-, moderate-, or high-quality study, respectively. Discrepancies were resolved by consensus and discussion.
The strength of the associations between DM and glioma was measured by odds ratios (ORs) with 95% confidence intervals (95% CIs). Between study heterogeneity was assessed by Chi-square test, and was quantified using the I2 statistic (ranging from 0% to 100%), which was defined as the percentage of the observed between study variability that is due to heterogeneity rather than chance. A random-effects model (DerSimonian–Laird method) was used. Publication bias was conducted if more than ten studies were included. All statistical tests were performed using RevMan 5.1 software (Nordic Cochrane Center, Copenhagen, Denmark). The value of P < 0.05 was considered significant. All the P values were two-sided.
| > Results|| |
After a comprehensive literature search applying our inclusion criteria, ten relevant studies which comprised 5,829,250 subjects were identified in the final analysis. Six studied provided the data of mean age. All studies were assessed by NOS. The quality scores ranged from 7 to 9, suggesting that the methodological quality was acceptable. The main study characteristics are summarized in [Table 1] and [Table 2].
|Table 2: Quality scores of studies using Newcastle–Ottawa Scale (maximum score of 9)|
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Quantitative data synthesis
As shown in [Figure 1], a statistically significant association between DM and glioma risk was fond (OR = 0.84; 95% CI, 0.73–0.97; P = 0.02). In the subgroup analysis of age group, young population with DM showed decreased glioma risk (OR = 0.83; 95% CI, 0.70–0.98; P = 0.02); [Figure 2], whereas old population with DM did not show a significant association (OR = 0.87; 95% CI, 0.65–1.16; P = 0.34). In the subgroup analysis of gender, male patients with DM showed decreased glioma risk (OR = 0.82; 95% CI, 0.68–0.99; P = 0.04); [Figure 3], whereas female population with DM did not show a significant association (OR = 0.93; 95% CI, 0.70–1.24; P = 0.63). Publication bias was not performed because only ten studies were included in this meta-analysis.
|Figure 2: Subgroup analysis by age on the association between diabetes and risk of glioma|
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|Figure 3: Subgroup analysis by gender on the association between diabetes and risk of glioma|
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| > Discussion|| |
This current meta-analysis of ten studies including 5,829,250 subjects systematically evaluated the association between DM and glioma risk. The results indicated that DM patients had lower risk for developing glioma. In the subgroup analysis by age, glioma risk was decreased in young patients with DM, suggesting a possible influence among age and DM. In the subgroup analysis by age, glioma risk was decreased in male patients with DM, suggesting a possible influence among gender and DM. There were only three or four studies in subgroup analysis. Thus, more studies are needed to confirm if age and gender could influence the glioma risk in DM patients.
Several mechanisms have been proposed to explain links between DM and increased cancer risk, including deregulation of insulin and insulin-like growth factor signaling, obesity and inflammation, and metabolic symbiosis; moreover, ER stress and autophagy have also emerged as important cellular mechanisms linking DM to cancer. However, the reason of why DM could reduce the risk of glioma is not known. Some recent studied suggested that metformin might provide this protective effect. Yu et al. indicated that temozolomide in combination with metformin synergistically inhibits the glioma stem cells proliferation through downregulation of AKT-mammalian target of rapamycin (mTOR) signaling pathway. Sesen et al. also suggested that metformin induces decreased proliferation, cell cycle arrest, autophagy, apoptosis, and cell death in vitro with a concomitant activation of AMP-activated protein kinase (AMPK), Redd1 and inhibition of the mTOR pathway. Sato et al. showed that metformin promoted FOXO3 activation and differentiation via AMPK activation, which was sensitive to extracellular glucose availability.
The present meta-analysis should be interpreted with caution, several limitations merit consideration. First, due to lacking of the original data of the eligible studies, I could not perform other subgroup analyses based on DM type, life style. Second, the numbers of published studies were not sufficient for a comprehensive analysis, particularly for age. However, our meta-analysis also had some merits. First, I investigated the association between DM and glioma risk in different age group. Second, there was low heterogeneity in this meta-analysis.
This meta-analysis suggested that DM may be associated with the reduced glioma risk. Further studies with a larger sample size are needed to further assess the presence of an association.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]