Clinical Significance of Exposure to Microplastics and the Risk of Diabetes Mellitus in Humans: A Systematic Review.

Microplastics and nanoplastics are pervasive environmental contaminants present in food, water, and air. Many studies have shown bioaccumulation of microplastics in human organs such as the lungs, colon, blood, and even placental tissue. Microplastics are potentially linked to many diseases such as colorectal cancer, lung cancer, obesity, metabolic syndrome, coronary artery disease, and dementia. There is also a potential link between microplastic exposure and diabetes. The incidence of diabetes is rapidly increasing across all countries globally. We conducted this systematic review to study the potential link between microplastic exposure and diabetes or adverse glycemic control in diabetics. A systematic search strategy was used, as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. We searched PubMed, Embase, Scopus, Google Scholar, and Cochrane. A total of 1,239 records were identified, of which 141 duplicates were removed, and 1,098 articles were screened. A total of six studies were included in the results. A meta-analysis could not be conducted as all articles were heterogeneous in exposure to microplastics, methods, etc. Two studies directly measured microplastic levels, one in urine samples of pregnant patients and another in blood serum. Both studies found a statistical significance of higher microplastic levels and worsening of diabetes control. Two studies assessed exposure by proxy-based methods and questionnaires. Participants consisted of people who consumed food in heated plastics and plastic bottled water. These studies found a correlation of higher HbA1c and increased risk of diabetes mellitus, with one study explicitly mentioning increased risk of type 2 diabetes mellitus. Two ecological studies where microplastic exposure was obtained from environmental data showed a higher prevalence of diabetes in populations where exposure was higher. While our data indicate an association between microplastic exposure and diabetes, the absence of large, prospective cohort studies currently precludes the establishment of a causal relationship. As plastic pollution accelerates globally, addressing this critical knowledge gap through rigorous longitudinal research is essential.