Thyroid hormone ratios and diabetes in adults 65+ across 18 Chinese longevity areas
In a 2021 cross-sectional survey of 5,795 adults aged 65 and older in 18 Chinese longevity areas, lower FT3/FT4 and T3/T4 ratios were associated with higher odds of diabetes; this is an association, not proof of cause. [1]
Automatic summary · not editorially reviewed
The key findings
The 2021 cross-sectional survey enrolled 5,795 participants aged 65 and older across 18 longevity areas in China. [1]
Compared with the highest quarter of the FT3/FT4 ratio, the lowest quarter had higher adjusted odds of diabetes (OR 2.02, 95% CI 1.61–2.54). [1]
The authors conclude that lower FT3/FT4 and T3/T4 ratios are linearly and inversely associated with increased diabetes risk in this population. [1]
The source at a glance
- Study type / format
- Cross-sectional survey (abstract of a cohort study's 2021 wave)
- Population / context
- Adults aged 65 years and older in 18 longevity areas of China (5,795 participants).
- Summary based on
- Study abstract
- Original publication
- August 1, 2026
Survey of adults 65+ in 18 longevity areas
The study asked whether thyroid hormone measures relate to diabetes risk among people aged 65 and older in longevity areas of China. Data came from the 2021 cross-sectional survey of the Healthy Ageing and Biomarkers Cohort Study, which enrolled 5,795 participants across 18 longevity areas. Participants averaged 85.25 years (standard deviation 11.56); 56.3% were female. Blood levels of free T3, free T4, T3, T4 and thyroid-stimulating hormone (TSH) were measured, and fasting blood glucose was determined. Diabetes was defined as fasting glucose of at least 7.0 mmol/L and/or self-reported physician-diagnosed diabetes.
Supporting source [1]
Lower ratios linked to higher diabetes odds
About 16.1% of participants had diabetes. After adjustment for confounding factors, the odds of diabetes were higher in the lowest quarter (Q1) of the FT3/FT4 ratio than in the highest quarter (Q4): odds ratio 2.02 (95% confidence interval 1.61–2.54). Q2 and Q3 also showed higher odds (1.72 and 1.37). For the T3/T4 ratio, Q1 versus Q4 had an odds ratio of 2.16 (1.71–2.73), with Q2 at 1.70 and Q3 at 1.51. The authors describe both ratios as showing linear inverse associations with diabetes.
Supporting source [1]
Cross-sectional design limits causal reading
The conclusion states that lower FT3/FT4 and T3/T4 ratios are linearly and inversely associated with an increased risk of diabetes in this population. Because the survey is cross-sectional, hormone levels and diabetes were assessed at the same time, so the data cannot show which came first or whether thyroid hormones influence diabetes. The abstract reports adjusted associations only; it does not establish a mechanism or a benefit of any intervention.
Supporting source [1]
How to interpret this
Abstract only; the full text was not reviewed. The design is cross-sectional, so timing and causality cannot be determined, and the abstract reports no follow-up. Findings apply to adults aged 65 and older in 18 longevity areas of China and are associations, not causal effects.
Based on the study abstract; the full paper, tables and supplementary data were not reviewed.
Source & supporting passages
Chen SR, Tan YJ, Chen JH, Chen C, Ma XY, Yang YX, Fu XS, Zhu ZY, Yang JJ, Li ZP, Sun PJ, Wang J, Zhang ZH, Meng X, Li Y, Lyu YB, Shi XM. · europepmc.org · August 1, 2026