Inflammatory mediator gene polymorphisms and gestational diabetes: a review of the literature

The incidence of gestational diabetes (GD) is rising worldwide, in parallel with obesity and type 2 diabetes. Obesity and GD are conditions that have in common a state of chronic, low-grade subclinical inflammation characterized by abnormal production of cytokines and mediators. Genetic polymorphisms may influence the production of inflammatory mediators and predispose to different disorders, including diabetes. The aim of this study was to review the existing literature on the relationship between inflammatory mediator gene polymorphisms and GD. The search in PubMed was restricted to articles published in English, from January 1990 to December 2010. Eight studies were included. These publications evaluated 13 different SNPs and six inflammatory mediators in the blood of women with GD. Gene polymorphisms related to leptin, mannose-binding lectin (MBL) and RAGE (receptor for advanced glycation end products) were individually evaluated in a single study each. Leptin and MBL plasma levels were also evaluated in two studies. The participants included in the studies were ethnically different, but matched with controls. Different criteria were adopted to select the participants. Seven of the eight studies included took into consideration the BMI of patients and controls. Due to the heterogeneity and limited number of studies on GD and inflammatory gene polymorphisms, we could not pool together any of the results or perform any additional analyses of the existing data. Since the existing findings come from isolated studies with mostly small sample sizes, there is a need for new, larger, properly designed studies of good methodological quality.