Iron Overload and Gestational Diabetes

What This Pregnancy Related Condition Tells us About How Iron Can Accelerate Diabetes

Gestational diabetes is diabetes that develops over the course of a woman’s pregnancy, and research seems to suggest that iron accelerates it.

Let’s look a this review first.

It was published in 2017 in The American Journal of Clinical Nutrition by C. Zhang at The National Institute of Child Health and Development and entitled “Dietary Iron Intake, Iron Status and Gestational Diabetes”.

Interesting Points

First, they review how iron overload can damage the cells in the pancreas that produce insulin by creating oxidative stress:

Free iron, with its strong pro-oxidant properties and consequent ability to generate reactive oxygen species, can contribute to increased oxidative stress and cellular damage and, hence, may be potentially hazardous in excess (1).

The pancreatic β cells are vulnerable to oxidative stress because their antioxidative defense mechanisms are particularly weak (2).

Although adequate iron is critical to normal β cell function and glucose homeostasis, studies based on mouse models of hereditary or dietary iron overload show that excess iron may disrupt glucose homeostasis by several potential mechanisms involving multiple tissues and organs.

For example, oxidative stress from excess iron accumulation can lead to β cell damage and apoptosis and, consequently, contribute to decreased insulin secretion (3).

Next they review how high levels of iron affect the liver, and insulin resistance.

High iron stores in the liver may induce insulin resistance by impairing insulin signaling and by attenuating the liver’s ability to extract insulin (4, 5).

In adipocytes, excess iron can diminish insulin-induced glucose transport, whereas in the muscles it may lead to a switch from glucose to fatty acid oxidation (6, 7).

This is important, because high iron levels in the liver are not necessarily reflected in a blood test, unless ferritin levels (iron storage protein) are measured.

The most reliable blood test that indicates if BODY iron stores are high is serum ferritin, the iron storage protein that can be measured in blood.

The authors note the following regarding serum ferritin levels and gestational diabetes:

Serum Ferritin (SF) concentration, an indicator of iron stores, has been most often examined in relation to the risk of gestational diabetes mellitus (GDM). A significant and positive association between SF concentration and GDM has been observed

SF concentrations in both the first and second trimesters were significantly and positively associated with a subsequent risk of GDM, even after accounting for inflammation measured via CRP levels.

One of the meta-analyses (37) that included 4 prospective studies (42, 43, 46, 57), women with the highest SF concentrations had a >3-fold greater risk of GDM compared with those with the lowest concentrations (pooled RR: 3.22; 95% CI: 1.73, 6.00).

Comment- Two Accelerating Factors to Consider