Typically, the serum selenium concentration levels are significantly lower in women with gestational diabetes than in healthy pregnant women. The differences are especially remarkable in non-Caucasian pregnant women and in pregnant women in the third trimester. That is the finding of a recent meta-analysis and systematic review of the relevant literature from observational studies [Kong 2016].
Selenium and gestational diabetes
Gestational diabetes is defined as any degree of glucose intolerance that occurs with the onset of pregnancy. A physiological insulin resistance beginning in the second trimester and progressing through the third trimester is fairly typical of pregnancies. Expecting mothers generally need increased insulin secretion to maintain normal blood glucose levels. Impairment of the needed compensatory increases in insulin secretion leads to a diagnosis of gestational diabetes [Kong 2016].
Selenium is an essential micronutrient. It is a component of antioxidant selenoproteins that have a protective effect against oxidative stress and inflammation [Burk 2002].
The relationship of serum selenium levels to gestational diabetes is important for the following reasons [Kong 2015]:
- Low serum selenium concentrations may leave the pregnant women and the fetuses more susceptible to the harmful effects of oxidative stress.
- Poor serum selenium status may aggravate insulin resistance in pregnant women leading to the aggravation of the gestational diabetes.
The mechanisms by which selenium status affects insulin resistance and blood glucose levels are not known; not enough studies of the mechanisms have been done to date.
Likewise, it is not known which comes first. Does low selenium status contribute to the development of gestational diabetes, or is the low selenium status a consequence of having developed gestational diabetes, which, then, further aggravates the gestational diabetes?
Benefits of moderate Se supplementation to pregnant women
Several studies have shown that moderate supplementation of pregnant women — 50 – 100 micrograms per day — confers a number of beneficial health outcomes:
- Reduced oxidative stress [Tara 2010]
- Reduced incidence of hypothyroidism and reduced thyroid inflammation [Negro 2007]
- Reduced incidence of pregnancy-induced high blood pressure [Han 1994]
- Reduced risk of pre-eclampsia [Rayman 2014]
- Reduced risk of the pre-labor rupture of membranes [Tara 2010]
- Reduced risk of postpartum depression [Mokhber 2011]
What are low serum/plasma selenium levels?
The best estimates of serum/plasma selenium levels to date are as follows [Hurst 2010]:
- serum/plasma selenium levels lower than 100 micrograms per liter are below normal
- serum/plasma selenium levels between 110 and 118 seem to be the level at which selenoprotein P approaches optimal activity
- serum selenium concentrations between 120 and 150 micrograms per liter are the “putative beneficial range”
In the meta-analysis summarized in this article, the following values were typical for pregnant women diagnoses with gestational diabetes (mean ± standard deviation):
- 34.7 ± 8.7 micrograms per liter
- 51.7 ± 11.7 micrograms per liter
- 63.5 ± 12.0 micrograms per liter
- 85.1 ± 5.4 micrograms per liter
Summing up: serum selenium status and gestational diabetes
Given that the incidence of gestational diabetes is increasing and given that the consequences of gestational diabetes – both acute and long-term – can be severe, the topic of serum selenium status and gestational diabetes is relevant and worthy of attention.
We need more studies of the selenium-gestational diabetes relationship with consistent measurements of selenium status, consistent values for glucose tolerance, and consistent clinical data about the pregnant women with gestational diabetes.
To the extent that selenium supplementation is needed, the best formulation is the high-selenium yeast formulation.
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Disclaimer: The information presented in this review article is not intended as medical advice and should not be construed as such.