Effect of Taking a Single Tablet of Iron on Insulin Secretion

Insulin Secretion Clinical Trial

Official title:

Acute Effect of a Single Dose of Oral Iron on Pancreatic Beta Cell Function in Healthy Individuals: a Quasi-experimental Single Arm Before-and-after (Pre-post) Study

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT05238987
• Other study ID #: IRB min.13294 Dt.26.08.2020
• Status: Completed
• Phase: N/A
• Start date: October 10, 2020
• Est. completion date: September 16, 2021

Study information

• Verified date: February 2022
• Source: Christian Medical College, Vellore, India
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Oral supplementation with highly bioavailable forms of iron, such as ferrous sulphate, is the treatment of choice for iron-deficiency anemia. Iron from ferrous sulphate is efficiently absorbed in the duodenum, resulting in a rapid increase in transferrin saturation and appearance of "free iron" or non-transferrin bound iron (NTBI) in blood. NTBI is highly reactive and can catalyze the generation of reactive oxygen species and cause oxidative tissue damage.

Human pancreatic beta cells are known to express ZIP14, a transporter that has been implicated in uptake of NTBI from blood. In vitro and animal studies have shown that iron loading in beta cells can result in impaired insulin secretion. However, there are no human studies that have looked at the acute effects of oral iron intake on insulin secretion.

In this study, we plan to look at the effect of a single oral dose of ferrous sulphate on insulin secretion kinetics in healthy individuals. A single arm before-and-after (pre-post) study design will be used. Consenting individuals who meet the participation criteria will undergo a 75g oral glucose tolerance test (OGTT) to document baseline insulin secretion kinetics. One week later, OGTT will be repeated after administering a single dose of ferrous sulphate (120 mg of elemental iron) 2 hours prior to the test. Iron-induced change in insulin secretion kinetics will be documented. In addition, we will determine changes in glucose tolerance, insulin resistance and insulin clearance rates.

Description:

Oral iron supplementation is the treatment of choice in patients with iron deficiency anemia. In several developing countries, including India, iron is routinely supplemented to pregnant women, especially during the second and third trimesters of pregnancy owing to the increased iron requirement for the placenta and growing fetus.

Oral administration of iron is preferred to intravenous administration because it is effective, relatively cheap and safe. There are many different oral iron preparations and most of them contain iron in the ferrous form (ferrous sulphate, ferrous fumarate, ferrous gluconate, ferrous ascorbate etc.). Although it has been shown that all these preparations are equally effective in increasing hemoglobin levels, ferrous sulphate, being easily available and economical, is the most prescribed iron preparation.

Iron is absorbed in the duodenum. Dietary iron is usually in the ferric form and must be reduced to the ferrous form prior to absorption. This reduction reaction is catalyzed by duodenal ferrireductases (such as duodenal cytochrome b) and is aided by gastric HCl and other reducing substances in the diet, such as vitamin C (ascorbic acid). Administration of iron in the ferrous form (e.g., ferrous sulphate) circumvents this step, thus making it readily bioavailable. Ferrous iron is transported across the luminal membrane of the enterocytes via divalent metal transporter-1 (DMT-1). Iron is then transported across the basolateral membrane (into blood) by another transporter, ferroportin. Hepcidin, a peptide hormone synthesized and secreted by the liver, binds to and degrades ferroportin, thus reducing intestinal iron absorption.

In the blood, iron is transported bound to the plasma protein, transferrin, which binds iron with high affinity. Transferrin is normally saturated to about 30 to 35% of its total iron binding capacity, leaving a large reserve to bind additional iron. In conditions of iron overload, such as hemochromatosis or in patients with thalassemia, transferrin saturation can increase significantly. When transferrin saturation increases beyond 60% and especially as it approaches 80%, a small but significant amount of iron circulates in blood that is not bound to transferrin. This fraction, called "labile iron" or non-transferrin bound iron (NTBI), is highly reactive and can cause oxidative tissue damage.

NTBI is rapidly cleared from circulation, mainly by hepatocytes. It has been shown that ZIP14 is physiologically the most important transporter that transports NTBI into hepatocytes. Recently, it was shown that ZIP14 is also expressed on human pancreatic beta cells and that it may mediate NTBI uptake by these cells. Several in vitro and animal studies have shown that iron overload impairs pancreatic beta cell function. Patients with hemochromatosis are known to accumulate iron in the beta cells, resulting in diabetes due to decreased insulin secretory capacity. On the other hand, iron chelation or dietary iron restriction improves insulin secretion in mouse models of diabetes. Similarly, iron chelation in hemochromatosis and thalassemia also improved insulin secretion. These studies prove a strong link between increased iron and impaired beta cell function.

It has been shown that, following a single dose of ferrous sulphate (containing 60-100 mg of elemental iron), transferrin saturation increases rapidly and peaks (at ~ 80%) 2 hours after administration. This is associated with a significant increase in NTBI, which also peaks at 2 hours. Given that oral iron administration increases NTBI in blood and that pancreatic beta cells take up NTBI via ZIP14, we hypothesized that oral iron may lead to increased beta cell iron levels which may then cause impaired insulin secretion

In order to test this hypothesis, we plan to conduct a quasi-experimental single arm before-and-after study, where insulin secretion kinetics will be determined at baseline and after a single dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy men.

Healthy male volunteers will be recruited from among the staff of Christian Medical College, Vellore after obtaining written informed consent.Participants will undergo a 75g oral glucose tolerance tests (OGTT) to document baseline insulin secretion kinetics. One week later, the OGTT will be repeated after a single dose of ferrous sulphate (120 mg of elemental iron) given 2 hours before the test. Serum levels of glucose, insulin, C-peptide, serum iron and transferrin saturation will be measured during both OGTT. The effects of iron on insulin secretion kinetics will be documented. In addition, we will determine if changes occur in glucose tolerance, insulin resistance and insulin clearance rates.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 15
• Est. completion date: September 16, 2021
• Est. primary completion date: September 16, 2021
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 18 Years to 60 Years

Eligibility

Inclusion Criteria:

BMI - 18 to 30 kg/m^2

Exclusion Criteria:

1. Known case of diabetes mellitus/pre-diabetes

2. History of chronic inflammatory disease

3. Anemia (detection of pallor on examination). Absence of anemia will be confirmed by hemoglobin estimation done at the time of baseline OGTT based on WHO criteria.

4. On iron supplementation

5. History of any gastrointestinal disorders that might affect absorption of iron/glucose

Related Conditions & MeSH terms

• Insulin Secretion

Intervention

Dietary Supplement:
• Ferrous sulphate
Single dose of ferrous sulphate (120 mg of elemental iron)

Locations

Country	Name	City	State
India	Christian Medical College	Vellore	Tamil Nadu

Sponsors (1)

Lead Sponsor	Collaborator
Christian Medical College, Vellore, India

Country where clinical trial is conducted

India, 

References & Publications (21)

Abraham D, Rogers J, Gault P, Kushner JP, McClain DA. Increased insulin secretory capacity but decreased insulin sensitivity after correction of iron overload by phlebotomy in hereditary haemochromatosis. Diabetologia. 2006 Nov;49(11):2546-51. Epub 2006 Sep 22. — View Citation

Auerbach M, Adamson JW. How we diagnose and treat iron deficiency anemia. Am J Hematol. 2016 Jan;91(1):31-8. doi: 10.1002/ajh.24201. Epub 2015 Nov 17. Review. — View Citation

Backe MB, Moen IW, Ellervik C, Hansen JB, Mandrup-Poulsen T. Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress. Annu Rev Nutr. 2016 Jul 17;36:241-73. doi: 10.1146/annurev-nutr-071715-050939. Epub 2016 May 4. Review. — View Citation

Blesia V, Patel VB, Al-Obaidi H, Renshaw D, Zariwala MG. Excessive Iron Induces Oxidative Stress Promoting Cellular Perturbations and Insulin Secretory Dysfunction in MIN6 Beta Cells. Cells. 2021 May 9;10(5). pii: 1141. doi: 10.3390/cells10051141. — View Citation

Brissot P, Ropert M, Le Lan C, Loréal O. Non-transferrin bound iron: a key role in iron overload and iron toxicity. Biochim Biophys Acta. 2012 Mar;1820(3):403-10. doi: 10.1016/j.bbagen.2011.07.014. Epub 2011 Aug 9. Review. — View Citation

Castillo MJ, Scheen AJ, Letiexhe MR, Lefèbvre PJ. How to measure insulin clearance. Diabetes Metab Rev. 1994 Jul;10(2):119-50. Review. — View Citation

Coffey R, Knutson MD. The plasma membrane metal-ion transporter ZIP14 contributes to nontransferrin-bound iron uptake by human ß-cells. Am J Physiol Cell Physiol. 2017 Feb 1;312(2):C169-C175. doi: 10.1152/ajpcell.00116.2016. Epub 2016 Nov 30. — View Citation

Cooksey RC, Jones D, Gabrielsen S, Huang J, Simcox JA, Luo B, Soesanto Y, Rienhoff H, Abel ED, McClain DA. Dietary iron restriction or iron chelation protects from diabetes and loss of beta-cell function in the obese (ob/ob lep-/-) mouse. Am J Physiol Endocrinol Metab. 2010 Jun;298(6):E1236-43. doi: 10.1152/ajpendo.00022.2010. Epub 2010 Mar 30. — View Citation

Dresow B, Petersen D, Fischer R, Nielsen P. Non-transferrin-bound iron in plasma following administration of oral iron drugs. Biometals. 2008 Jun;21(3):273-6. Epub 2007 Sep 13. — View Citation

Farmaki K, Angelopoulos N, Anagnostopoulos G, Gotsis E, Rombopoulos G, Tolis G. Effect of enhanced iron chelation therapy on glucose metabolism in patients with beta-thalassaemia major. Br J Haematol. 2006 Aug;134(4):438-44. Epub 2006 Jul 4. — View Citation

Fuqua BK, Vulpe CD, Anderson GJ. Intestinal iron absorption. J Trace Elem Med Biol. 2012 Jun;26(2-3):115-9. doi: 10.1016/j.jtemb.2012.03.015. Epub 2012 May 8. Review. — View Citation

Geisser P, Burckhardt S. The pharmacokinetics and pharmacodynamics of iron preparations. Pharmaceutics. 2011 Jan 4;3(1):12-33. doi: 10.3390/pharmaceutics3010012. — View Citation

Goddard AF, James MW, McIntyre AS, Scott BB; British Society of Gastroenterology. Guidelines for the management of iron deficiency anaemia. Gut. 2011 Oct;60(10):1309-16. doi: 10.1136/gut.2010.228874. Epub 2011 May 11. — View Citation

Hansen JB, Tonnesen MF, Madsen AN, Hagedorn PH, Friberg J, Grunnet LG, Heller RS, Nielsen AØ, Størling J, Baeyens L, Anker-Kitai L, Qvortrup K, Bouwens L, Efrat S, Aalund M, Andrews NC, Billestrup N, Karlsen AE, Holst B, Pociot F, Mandrup-Poulsen T. Divalent metal transporter 1 regulates iron-mediated ROS and pancreatic ß cell fate in response to cytokines. Cell Metab. 2012 Oct 3;16(4):449-61. doi: 10.1016/j.cmet.2012.09.001. Epub 2012 Sep 20. — View Citation

Jenkitkasemwong S, Wang CY, Coffey R, Zhang W, Chan A, Biel T, Kim JS, Hojyo S, Fukada T, Knutson MD. SLC39A14 Is Required for the Development of Hepatocellular Iron Overload in Murine Models of Hereditary Hemochromatosis. Cell Metab. 2015 Jul 7;22(1):138-50. doi: 10.1016/j.cmet.2015.05.002. Epub 2015 May 28. — View Citation

Kapil U, Kapil R, Gupta A. National Iron Plus Initiative: Current status & future strategy. Indian J Med Res. 2019 Sep;150(3):239-247. doi: 10.4103/ijmr.IJMR_1782_18. Review. — View Citation

Matsuda M, DeFronzo RA. Insulin sensitivity indices obtained from oral glucose tolerance testing: comparison with the euglycemic insulin clamp. Diabetes Care. 1999 Sep;22(9):1462-70. — View Citation

McClain DA, Abraham D, Rogers J, Brady R, Gault P, Ajioka R, Kushner JP. High prevalence of abnormal glucose homeostasis secondary to decreased insulin secretion in individuals with hereditary haemochromatosis. Diabetologia. 2006 Jul;49(7):1661-9. Epub 2006 Mar 15. — View Citation

Nemeth E, Tuttle MS, Powelson J, Vaughn MB, Donovan A, Ward DM, Ganz T, Kaplan J. Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. Science. 2004 Dec 17;306(5704):2090-3. Epub 2004 Oct 28. — View Citation

Solomon TPJ. Sources of Inter-individual Variability in the Therapeutic Response of Blood Glucose Control to Exercise in Type 2 Diabetes: Going Beyond Exercise Dose. Front Physiol. 2018 Jul 13;9:896. doi: 10.3389/fphys.2018.00896. eCollection 2018. Review. — View Citation

Van Cauter E, Mestrez F, Sturis J, Polonsky KS. Estimation of insulin secretion rates from C-peptide levels. Comparison of individual and standard kinetic parameters for C-peptide clearance. Diabetes. 1992 Mar;41(3):368-77. — View Citation

* Note: There are 21 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in insulin secretion kinetics	Change in insulin secretion rate as determined by deconvolution of C-peptide levels in blood during an oral glucose tolerance test based on a previously published mathematical model (Van Cauter et al., 1992).	2 hours from intake of 120 mg of elemental iron
Primary	Change in disposition index	Disposition index is a measure of beta-cell function which is calculated as a product of insulin sensitivity and insulin secretion during an oral glucose tolerance test	2 hours from intake of 120 mg of elemental iron
Primary	Change in insulinogenic index	A measure of beta-cell function which calculates the increase in insulin secretion in response to increase in glucose concentration during an oral glucose tolerance test	2 hours from intake of 120 mg of elemental iron
Secondary	Change in glucose tolerance	Glucose tolerance will be determined by calculating the area under the curve (AUC) of glucose levels during oral glucose tolerance test	2 hours from intake of 120 mg of elemental iron
Secondary	Change in insulin sensitivity	Insulin sensitivity which is a measure of insulin action will be calculated using the Matsuda index (Matsuda and DeFronzo, 1999)	2 hours from intake of 120 mg of elemental iron
Secondary	Change in insulin clearance rate	Insulin clearance rate which is a measure of rate of disappearance of insulin from the blood will be calculated as described previously (Castillo et al., 1994)	2 hours from intake of 120 mg of elemental iron