Toxoplasma gondii Infection in Diabetes Mellitus Patients in China: Seroprevalence, Risk Factors, and Case-Control Studies

Abstract

The association between Toxoplasma gondii (T. gondii) infection and diabetes mellitus remains controversial. With the improvement of living standards, the prevalence rate of diabetes is steadily increasing in China. Thus, it is necessary to explore the possible association between toxoplasmosis and diabetes mellitus in China. Hence, case-control studies were conducted to explore the T. gondii seroprevalence and identify the risk factors and possible transmission routes of T. gondii infection in different types of diabetes, including type 1 diabetes (T1DM), type 2 diabetes (T2DM), and gestational diabetes (GDM) patients in China. Four hundred serum samples for each type of diabetes mellitus, matched with 400 control subjects for each group, were collected and examined for anti-T. gondii IgG and IgM antibodies using commercially available enzyme immunoassay kits. The total T. gondii seroprevalence in T1DM, T2DM, and GDM patients was 16.50%, 23.50%, and 21.25%, respectively. Each type of diabetes mellitus patients had a significantly higher T. gondii seroprevalence than the control subjects. Multivariate regression identified three variables as risk factors for T. gondii infection in diabetes patients, including keeping cats at home and consumption of raw oysters for T1DM patients and consumption of raw/undercooked meat and raw oysters for T2DM patients, which may help to guide future research and control policies in diabetes mellitus patients.

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

“…The remaining 25 papers were read as abstracts with 12 being rejected due to being literature reviews or animal studies. The residual 13 papers (Li et al 2018;Khalili et al 2018;Han et al 2018;Molan and Ismail 2017;Alvarado-Esquivela et al 2017;Saheb 2017;Nihad and Hamad 2017;Hemida et al 2017;Saki and Shafieenia 2016;Modrek et al 2015a;Siyadatpanah et al 2013;Shirbazou et al 2013;Gokce et al 2008), as summarised in Table 1, were read in full and three studies (Han et al 2018;Hemida et al 2017;Modrek et al 2015a) were excluded as they lacked a control group and hence did not meet the inclusion criteria. The references of the review articles did not add any new studies.…”

“…The references of the review articles did not add any new studies. Consequently, ten studies were retained for the final analysis (Li et al 2018;Khalili et al 2018;Molan and Ismail 2017;Alvarado-Esquivela et al 2017;Saheb 2017;Nihad and Hamad 2017;Saki and Shafieenia 2016;Siyadatpanah et al 2013;Shirbazou et al 2013;Gokce et al 2008) (Table 2).…”

“…The majority of the studies were conducted in the last 5 years with a significant output of eight studies from the Middle East (Iran, n = 4; Iraq, n = 3; and Turkey, n = 1), followed by China and Brazil with one study each. Six studies (Li et al 2018;Khalili et al 2018;Molan and Ismail 2017;Alvarado-Esquivela et al 2017;Saheb 2017;Gokce et al 2008) defined their diabetic case subjects according to the type of diabetes while the remaining four studies used the term "diabetic" (Table 1). Four studies (Li et al 2018;Nihad and Hamad 2017;Saki and Shafieenia 2016;Siyadatpanah et al 2013) recruited cases and control subjects from hospitals while another four studies (Khalili et al 2018;Molan and Ismail 2017;Alvarado-Esquivela et al 2017;Saheb 2017) recruited their cases and control subjects from clinics.…”

“…The two residual studies did not specify the source of recruitment of the cases and controls. With regard to case-control matching for age and gender, only six studies (Li et al 2018;Khalili et al 2018;Alvarado-Esquivela et al 2017;Siyadatpanah et al 2013;Shirbazou et al 2013;Gokce et al 2008) performed this. All studies employed commercially available laboratory IgG techniques to determine T. gondii infection status of their case and control subjects.…”

“…One of the most striking findings to come out of this meta-analysis is that little human data exists on the relationship between T. gondii and T2DM despite the fact that T. gondii infects approximately one third of the world's population (Centers for Disease Control and Prevention 2015; Halonen and Weiss 2013). Seven (Li et al 2018;Molan and Ismail 2017;Saheb 2017;Nihad and Hamad 2017;Saki and Shafieenia 2016;Shirbazou et al 2013;Gokce et al 2008) of the 10 studies found that subjects with T2DM had significantly higher (p < 0.05) prevalence rates of T. gondii when compared to healthy controls, therefore concluding that a significant relationship exists between T. gondii infection and T2DM. The remaining three studies (Khalili et al 2018;Alvarado-Esquivela et al 2017;Siyadatpanah et al 2013) did not find a statistically significant difference in prevalence of the parasite in diabetic and non-diabetic individuals.…”