You will be provided with a reference and some statements. Please determine whether each statement is 'supported', 'unsupported', or 'unknown' with respect to the reference. Please note:
First, assess whether the reference contains any valid content. If the reference contains no valid information, such as a 'page not found' message, then all statements should be considered 'unknown'.
If the reference is valid, for a given statement: if the facts or data it contains can be found entirely or partially within the reference, it is considered 'supported' (data accepts rounding); if all facts and data in the statement cannot be found in the reference, it is considered 'unsupported'.

You should return the result in a JSON list format, where each item in the list contains the statement's index and the judgment result, for example:
[
    {
        "idx": 1,
        "result": "supported"
    },
    {
        "idx": 2,
        "result": "unsupported"
    }
]

Below are the reference and statements:
<reference>
1. Nutrients. 2023 Feb 27;15(5):1198. doi: 10.3390/nu15051198.

Associations between Plasma Essential Metals Levels and the Risks of All-Cause 
Mortality and Cardiovascular Disease Mortality among Individuals with Type 2 
Diabetes.

Li Z(1), Wang R(1), Long T(1), Xu Y(1), Guo H(1), Zhang X(1), He M(1).

Author information:
(1)Department of Occupational and Environmental Health, State Key Laboratory of 
Environmental Health for Incubating, School of Public Health, Tongji Medical 
College, Huazhong University of Science and Technology, Wuhan 430030, China.

Epidemiological evidence regarding the possible link between multiple essential 
metals levels and all-cause mortality and cardiovascular disease (CVD) mortality 
among type 2 diabetes (T2D) patients is sparse. Here, we aimed to evaluate the 
longitudinal associations between 11 essential metals levels in plasma and 
all-cause mortality and CVD mortality among T2D patients. Our study included 
5278 T2D patients from the Dongfeng-Tongji cohort. LASSO penalized regression 
analysis was used to select the all-cause and CVD mortality-associated metals 
from 11 essential metals (iron, copper, zinc, selenium, manganese, molybdenum, 
vanadium, cobalt, chromium, nickel, and tin) measured in plasma. Cox 
proportional hazard models were used to estimate hazard ratios (HRs) and 95% 
confidence intervals (CIs). Results: With a median follow-up of 9.8 years, 890 
deaths were documented, including 312 deaths of CVD. LASSO regression models and 
the multiple-metals model revealed that plasma iron and selenium were negatively 
associated with all-cause mortality (HR: 0.83; 95%CI: 0.70, 0.98; HR: 0.60; 
95%CI: 0.46, 0.77), whereas copper was positively associated with all-cause 
mortality (HR: 1.60; 95%CI: 1.30, 1.97). Only plasma iron has been significantly 
associated with decreased risk of CVD mortality (HR: 0.61; 95%CI: 0.49, 0.78). 
The dose-response curves for the association between copper levels and all-cause 
mortality followed a J shape (Pfor nonlinear = 0.01). Our study highlights the 
close relationships between essential metals elements (iron, selenium, and 
copper) and all-cause and CVD mortality among diabetic patients.

DOI: 10.3390/nu15051198
PMCID: PMC10005369
PMID: 36904197 [Indexed for MEDLINE]

Conflict of interest statement: The authors declare no conflict of interest.
</reference>

<statements>
1. Epidemiologic and mechanistic studies suggest that dysregulated plasma or serum levels of several metals are associated with increased risks of coronary heart disease (CHD), stroke, arrhythmias, and cardiovascular mortality, raising the question of whether intentional modulation (e.g., supplementation or chelation) could be preventive or therapeutic.
2. Among individuals with type 2 diabetes, higher plasma iron and selenium were associated with reduced all-cause mortality, while higher copper was linked with increased mortality; plasma iron was also significantly associated with lower CVD mortality.
3. In diabetic populations, higher plasma iron has been associated with lower all-cause and CVD mortality, whereas higher copper has been associated with increased mortality.
4. Iron, copper, and other metals show complex, often ambivalent associations with cardiovascular outcomes, and no clear preventive or therapeutic supplementation strategies have emerged; inappropriate modulation may be harmful.
</statements>

Begin the assessment now. Output only the JSON list, without any conversational text or explanations.