The association between Toxoplasma gondii and type 2 diabetes mellitus: a systematic review and meta-analysis of human case-control studies

Abstract

Objectives: An emerging field of research is examining the association of infectious and environmental pathogens with type 2 diabetes mellitus (T2DM). An understudied pathogen of interest is the protozoan parasite Toxoplasma gondii (T. gondii). The objective of this study was to investigate the possible correlation between T. gondii infection and T2DM. We conducted a systematic review and meta-analysis on the currently available T. gondii seroprevalence data from case-control studies looking at subjects with T2DM in comparison to healthy controls to estimate the risk of T2DM. Methods: Ten electronic databases were searched using specific Medical Subject Headings terms without language or date restrictions. Fixed and random effects models were used to determine odds ratios with statistical significance being set at 5.0%. Results: Ten publications reporting T. gondii seroprevalence from 4072 subjects met the eligibility criteria. Seven of these studies reported a significant association between T. gondii infection and T2DM (p < 0.05). The overall weighted prevalence of T. gondii infection in subjects with T2DM was 47.8% (range 6.4-65.1%) in comparison to 25.9% (range 3.2-59.0%) of healthy controls (p < 0.001). The common odds ratio, calculated using a random effects model, was 2.32 (95% CI 1.66-3.24, p < 0.001). Conclusions: T. gondii infection should continue to be regarded as a possible contributing factor in T2DM disease development. Further studies that include inflammatory biomarker analysis are warranted to determine the specific role of this parasite in the pathogenesis of T2DM.

First Age- and Gender-Matched Case-Control Study in Australia Examining the Possible Association between Toxoplasma gondii Infection and Type 2 Diabetes Mellitus: The Busselton Health Study

“…Recent systematic reviews and meta-analyses [22,33,34] conducted to determine the possible association between T.…”

Association of Toxoplasma Gondii Infection With Diabetes Mellitus Using Nested-PCR and Sequencing

“…It was deduced that seroprevalence of anti-T. gondii IgG is higher in T2DM cases than in the controls (P<0.0001). Accordingly, two meta-analysis studies have emphasized a potent association between Toxoplasma exposure and T2DM, but not T1DM [32,33]. The current study aimed to address the involved genotypes of T. gondii in the above groups using the nested-PCR technique and sequencing.…”

“…This organism can manipulate the host's immunity and survive the harsh molecular milieu in the body [31]. In addition, Toxoplasma has been speculated to be involved in triggering and or progression of pathophysiological processes of some autoimmune disorders, including DM [26,32,33]. Until now, chronic toxoplasmosis has been significantly correlated to thyroid disease, systemic sclerosis, rheumatoid arthritis, inflammatory bowel syndrome, and hypertension in T2DM patients [34,35].…”

“…The parasite elicits inflammatory markers such as tumor necrosis factor-α, tissue growth actor-β (TGF-β), nitric oxide synthase, and reactive oxygen species (ROS), which in turn establish chronic inflammatory condition [26]. On the other hand, the risk of insulin resistance and T2DM progression are remarkably associated with nitric oxide, ROS, and pro-inflammatory cytokines [26,32,44]. T. gondii infects all nucleated host cells, including fat tissue cells, which modifies inflammatory fat distribution and confers obesity as a primary risk factor of T2DM [45,46].…”

The Seroprevalence of Toxoplasma gondii and Associated Risk Factors Among Type 1 Diabetes Mellitus Patients in Abadan, Southwest Iran

“…In general, previous reports have shown that toxoplasmosis develops susceptibility to DM, and diabetic patients are more sensitive to be infected with T. gondii (5,9). This study aimed to evaluate anti-T. gondii IgG antibodies among T1DM patients using ELISA method.…”