Pregnant women with elevated levels of iron are at increased risk for gestational diabetes, according to research published in the journal Diabetic Medicine, titled “High maternal iron status, dietary iron intake and iron supplement use in pregnancy and risk of gestational diabetes mellitus: a prospective study and systematic review.”
High iron levels, as measured through dietary intake and biomarkers, are known to be linked to type 2 diabetes, but it was unclear whether an identical association exists when considering gestational diabetes mellitus.
To address this question, Amina Khambalia and colleagues from the Kolling Institute of Medical Research at the University of Sydney, Australia, conducted a systematic review using PubMed, MEDLINE, EMBASE and CINAHL databases, from 1995 to July 31, 2015, on all published work investigating the association between maternal iron status, iron intake, and the risk of developing gestational diabetes. The team also conducted a group study to examine first trimester iron stores in the body and subsequent risk of gestational diabetes.
The research team examined the levels of ferritin — a protein produced in metabolism that stores iron in tissues — along with C-reactive protein and soluble transferrin receptor in a group of 3,776 pregnant women in their first trimester. The data was then linked to medical records for information on maternal features and gestational diabetes diagnoses.
The results showed that of the 3,776 women examined, 3.4 percent developed gestational diabetes. Increased odds of gestational diabetes were found for ferritin, but not for soluble transferrin receptor.
In the systematic review, two studies of iron supplementation revealed there was no association with gestational diabetes, whereas two cohort studies found an association between gestational diabetes and dietary heme iron intake — the iron found in meats, seafood and poultry — but not in non-heme iron, which is derived from plants and iron-fortified food.
Results from a pooled analysis of case-control studies revealed there was an association between the increased risk of gestational diabetes and higher levels of ferritin, serum iron, and dietary heme iron intake.
“A review of the literature to date indicates that increased risk of gestational diabetes does not result from short exposures to iron supplements during pregnancy, but is associated with higher intakes of dietary [heme] iron during the preconception and early pregnancy period,” the research team wrote in a news release. “Further studies are warranted that better characterize iron’s role in the patho-physiological pathways that lead to gestational diabetes, that measure and compare multiple iron biomarkers in combination with dietary and supplemental sources of iron, and that identify high-risk populations for intervention studies.”