Original ArticleType 2 Diabetes Mellitus and Glioblastoma Multiforme-Assessing Risk and Survival: Results of a Large Retrospective Study and Systematic Review of the Literature

ObjectiveDespite studies showing a positive correlation between type 2 diabetes mellitus (DM2), a modifiable risk factor, and various cancer types, the link remains controversial in the setting of glioblastoma multiforme (GBM). In this study, we assessed whether DM2 and DM2-associated factors were associated with a higher risk of developing GBM and also determined if DM2 affected the survival of patients with GBM.MethodsA cross-sectional case-control study of 1144 GBM cases diagnosed between 2000 and 2013 of which 969 patients matched for age and sex was performed to assess the association between DM2, hyperlipidemia, and obesity with the incidence of GBM. A longitudinal study of the patients with GBM was also performed to assess the association between the effect of DM2 and GBM survival.ResultsNo association was seen between DM2, hyperlipidemia, obesity, and GBM. DM2 was associated with poorer survival in univariate testing yet not in multivariate testing. Diabetic patients with GBM had good glycemic control. Older patients had poorer survival and overall survival improved over years of study.ConclusionsDM2, hyperlipidemia, and obesity were not associated with increased risk of developing GBM, and DM2 itself does not seem to influence survival among these patients. This finding might be related to good glycemic control in this cohort. Survey of the literature consistently shows that hyperglycemia is associated with poorer survival. Our findings suggest that rather than the presence or absence of DM2, glycemic control seems to be more important in the survival of patients with GBM, which warrants future investigation.