Written by Harold Oster, MD. Results show that in type 2 diabetics, plasma levels of iron and selenium are negatively associated with overall mortality, iron levels are negatively associated with cardiovascular mortality, and copper levels are positively associated with all-cause mortality.
The prevalence of type 2 diabetes is increasing worldwide, leading to an increase in diabetic complications, including coronary artery disease, kidney failure, and stroke. Diabetics have a higher cardiovascular and overall mortality than nondiabetics1. Essential minerals, including metals and selenium (usually not considered a metal)2 cannot be produced in humans and are necessary for normal physiologic function3. Deficiency and excess intake of some essential minerals can lead to disease, and studies designed to determine optimal levels of these micronutrients have yielded mixed results4.
Zhaoyang Li et al. studied the associations between plasma levels of essential minerals and cardiovascular and all-cause mortality in diabetics. Five thousand two hundred seventy-eight diabetics were chosen based on defined inclusion criteria from the Dongfeng–Tongji cohort (a multi-year study of retired workers of the Dongfeng Motor Corporation in China). Plasma levels of essential minerals, including zinc, selenium, manganese, molybdenum, vanadium, cobalt, chromium, nickel, and tin were measured. Participants were assessed by questionnaire for smoking history and personal and family history of hypertension, cancer, and cardiovascular disease. Other factors known to affect mortality risk were tested, including body mass index, level of physical activity, lipid profile, diabetes control, blood pressure, and renal function. Participants were followed for a median of 9.8 years, and causes of death were determined by trained staff blinded to the above variables and the levels of minerals tested. A total of 890 deaths were identified, of which 312 were due to cardiovascular disease.
The authors used a logarithmic scale to analyze the association between levels of the minerals and mortality. Appropriate statistical techniques were applied to adjust for known covariates of mortality and to control for the significant correlations identified between many of the minerals.
The authors noted the following:
- Compared to survivors, those who died were more likely to be male, older, and have a longer duration of diabetes. Those who died also were more likely to smoke cigarettes, drink alcohol, have hypertension, hyperlipidemia, and a higher fasting blood glucose level.
- On a continuous logarithmic scale, each unit increase in the levels of iron and selenium was associated with decreased overall mortality, with hazard ratios (HR) of 0.83 and 0.6, respectively.
- On a continuous logarithmic scale, each unit increase in the level of copper was associated with increased overall mortality, with an HR of 1.6.
- Compared to the lowest quartile, the highest quartiles of levels of iron and selenium were associated with lower all-cause mortality, with HRs of 0.79 and 0.72, respectively.
- The highest quartile for the level of copper was associated with increased overall mortality compared to the lowest, with an HR of 1.5.
- Higher serum iron levels were associated with decreased cardiovascular mortality in the continuous and quartile models.
- The levels of the other tested minerals were not significantly associated with overall or cardiovascular mortality.
Results of the study suggest that in diabetics, plasma levels of iron and selenium are inversely associated with all-cause mortality, copper levels are positively associated with all-cause mortality, and iron levels are inversely associated with cardiovascular mortality. Limitations of the study include the following: Levels of minerals were tested only at baseline; dietary information on the intake of foods containing the tested minerals was not ascertained; and other than the single baseline test of fasting blood glucose, the severity of diabetes in the participants was unknown.
Source:Li, Zhaoyang, Ruixin Wang, Tengfei Long, Yali Xu, Huan Guo, Xiaomin Zhang, and Meian He. “Associations between Plasma Essential Metals Levels and the Risks of All-Cause Mortality and Cardiovascular Disease Mortality among Individuals with Type 2 Diabetes.” Nutrients 15, no. 5 (2023): 1198.
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
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Posted July 25, 2023.
Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.
References:
- Harding JL, Pavkov ME, Magliano DJ, Shaw JE, Gregg EW. Global trends in diabetes complications: a review of current evidence. Diabetologia. Jan 2019;62(1):3-16. doi:10.1007/s00125-018-4711-2
- PubChem. Selenium. 2023. https://pubchem.ncbi.nlm.nih.gov/compound/Selenium
- Godswill AG, Somtochukwu IV, Ikechukwu AO, Kate EC. Health benefits of micronutrients (vitamins and minerals) and their associated deficiency diseases: A systematic review. International Journal of Food Sciences. 2020;3(1):1-32.
- O’Connor EA, Evans CV, Ivlev I, et al. Vitamin and Mineral Supplements for the Primary Prevention of Cardiovascular Disease and Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. Jama. Jun 21 2022;327(23):2334-2347. doi:10.1001/jama.2021.15650
