Type 2 diabetes mellitus and risk of oral cancer and precancerous lesions: A meta-analysis of observational studies

SummaryObjectiveAssociations between type 2 diabetes mellitus (type 2 DM) and risk of oral cancer and precancerous lesions have been reported with controversial findings. We performed a meta-analysis to explore these associations.MethodsWe identified studies by a literature search of MEDLINE and EMBASE through May 31, 2014, and by searching the reference lists of pertinent articles. Summary relative risk (SRR) with 95% confidence interval (CI) was calculated with a random-effects model. Between- study heterogeneity was assessed using the Cochran’s Q and I2 statistics.ResultsA total of 13 studies (4 case-control and 9 cohort studies) on the association between type 2 DM and oral cancer were included. Overall analysis found that compared with non-diabetic individuals, individuals with type 2 DM had a significantly elevated incidence of oral cancer (SRR = 1.15, 95% CI: 1.02–1.29; Pheterogeneity = 0.277, I2 = 15.4%; 10 studies). Subgroup analyses found that duration of follow-up (⩾11 years) significantly altered this positive association. Type 2 DM was associated with increased oral cancer mortality (SRR = 1.41, 95% CI: 1.16–1.72; 4 studies). Meta-analysis of the four case-control studies showed a positive association between type 2 DM and risk of oral precancerous lesions (SRR = 1.85, 95%CI: 1.23–2.80; Pheterogeneity = 0.038, I2 = 57.5%). No significant public bias was found across these studies.ConclusionsThese findings of this meta-analysis indicate that compared with non-diabetic individuals, individuals with type 2 DM have an elevated risk of oral cancer and precancerous lesions development.