Selenium and Type 2 Diabetes

Selenium supplementation and the possible risk of developing type 2 diabetes, what do we know? This is a complex issue. Many different biological, hormonal, and environmental factors have an effect on the relationship.

Selenium and diabetes interrelationship
Observational evidence points to relevant sex differences in the selenium-diabetes interrelationship. There may be potential harmful effects in men living in selenium-rich areas and in men with high habitual selenium intake. Research shows potential benefits of selenium on diabetes risk in women selenium-deficient areas or in women with low selenium intake.

In a 2024 review, Demircan and a selenium research team headed by Prof Lutz Schomburg, Charité Berlin, investigated the current evidence for a relationship between selenium and type 2 diabetes. Recent evidence points to selenium intake and serum selenium status as relevant factors in the study of type 2 diabetes complications and prognosis.

Two studies based on data from the National Health and Nutrition Examination Survey (NHANES) in the United States have identified selenium intake and serum selenium status, respectively, as associated with the improved survival of type 2 diabetes patients [Demircan 2024].

Selenium Status and Diabetes and Its Co-Morbidities

With respect to co-morbidities linked to type 2 diabetes, Demircan et al noted that higher serum selenium status as compared to lower serum selenium status has been shown to have the following associations:

  • lower risk of heart failure, hypertension, and stroke
  • lower risk of all-cause mortality
  • lower risk of myocardial infarction, especially in females
  • reduced bio-markers of metabolic syndrome
The Role of Sex in Selenium and Diabetes Research

Demircan and Schomburg and the research team have explored the differing perspectives and concerns regarding the relationship between selenium and type 2 diabetes risk. In any study of the selenium-diabetes interaction, they underscore the importance of the following factors [Demircan 2024]:

  • the study participants’ baseline selenium status
  • the sex of the study participants
  • the health and disease conditions of the study participants

In their survey of the recent observational literature, Demircan et al found that there are relevant sex differences at work in the selenium-diabetes interrelation. Too often, research results based on study samples consisting mostly of male participants have been generalized to the whole population and have given a misleading impression [Demircan 2024].

Demircan et al note that the exact molecular mediators of the sex-specific effects of selenium on diabetes risk remain to be discovered.

Importance of Baseline Selenium Status in studies

In addition to the confusion caused by extrapolating from one sex to both sexes, there is a clearly recognizable danger in ignoring the role of baseline selenium status in selenium supplementation studies. Different study samples vary considerably in the serum selenium status of the participants. It is a mistake to combine the results from studies enrolling mostly selenium-replete individuals with the results from studies enrolling mostly selenium-deficient individuals [Demircan 2024].

Question of Reverse Causality in Observational Studies

Demircan et al note that that insulin resistance develops years before a diagnosis of type 2 diabetes is made. The insulin resistance promotes an increase in the secretion of Selenoprotein P from the liver. The increase in selenoprotein P secretion results in an increase in circulating selenium concentrations [Demircan 2024].

Thus, on the surface, higher serum selenium status may seem to be causing the development of type 2 diabetes. In fact, however, it is likely to be the other way round. The as yet undiagnosed insulin resistance is resulting in higher blood selenium concentrations long before the insulin resistance leads to a diagnosis of type 2 diabetes [Demircan 2024; Schomburg 2020].

Note: Insulin resistance is the condition in which the cells become less responsive to the effects of insulin. This leads to higher blood sugar levels.

Selenium Intake and Pregnancy

In the Odense Child Cohort study, low serum selenium in pregnancy was independently associated with increased risk of gestational diabetes and with offspring large for gestational age. Undertaking tests of serum selenium status during pregnancy could identify women at high risk for gestational diabetes who might benefit from selenium substitution [Demircan 2023].

Demircan et al raise the question as to whether selenium supplementation should be recommended for pregnant women together with iodine and folate supplementation [Demircan 2024].

Note: Gestational diabetes mellitus (GDM) is characterized by high concentrations of glucose in the blood and by insulin resistance. GDM typically develops during the second and third trimester of pregnancy. It frequently resolves post-partum, but it can result in long-term health risks [Demircan 2024].

Conclusion: Selenium Status and Diabetes Risk

Recent data indicate an important role for sex in the relationship between selenium status and type 2 diabetes risk and insulin resistance [Demircan 2024].

Pooling data from studies enrolling individuals with divergent baseline selenium status, with different sexes, with different health situations, and with supplementation with different selenium species and dosages and duration can result in misleading findings.

Recent observational evidence suggests that high selenium status has a beneficial effect on all-cause mortality risk in patients with type 2 diabetes and reduces macrovascular type 2 diabetes risk.

The mostly observational data about selenium status and diabetes risk do not permit any causal inference. However, the research findings to date
seem to advocate for selenium supplementation for women with limited selenium intakes and for women during pregnancy [Demircan 2024].

Selenium supplementation of pregnant women with limited dietary intakes holds promise in reducing risks of gestational diabetes, postpartum thyroiditis, and other pregnancy complications [Demircan 2024; Demircan 2023].

Sources

Demircan K, Chillon TS, Bang J, Gladyshev VN, Schomburg L. Selenium, diabetes, and their intricate sex-specific relationship. Trends Endocrinol Metab. 2024 Sep;35(9):781-792.

Demircan K, Jensen RC, Chillon TS, Jensen TK, Sun Q, Bonnema SJ, Hackler J, Korevaar TIM, Glintborg D, Schomburg L, Andersen MS. Serum selenium, selenoprotein P, and glutathione peroxidase 3 during early and late pregnancy in association with gestational diabetes mellitus: Prospective Odense Child Cohort. Am J Clin Nutr. 2023 Dec;118(6):1224-1234.

Schomburg L. The other view: the trace element selenium as a micronutrient in thyroid disease, diabetes, and beyond. Hormones (Athens). 2020 Mar;19(1):15-24.

The information summarized in this review article is not intended as medical advice. It should not be used as such.

 

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