Supplementary Material for: Higher risk of sarcopenia in older adults with type 2 diabetes: NHANES 1999-2018

Introduction: Recent studies suggested that sarcopenia may be a significant comorbidity of diabetes mellitus (DM). Nonetheless, studies with nationally representative data are scarce, and the changing trend of sarcopenia prevalence over time is largely unknown. Therefore, we aimed to estimate and compare the prevalence of sarcopenia in diabetic and non-diabetic United States (US) older population, and to explore the potential predictors of sarcopenia as well as the trend of sarcopenia prevalent in the past decades. Methods: Data was retrieved from the National Health and Nutrition Examination Survey (NHANES). Sarcopenia and DM were defined according to corresponding diagnosis criteria. Weighted prevalence was calculated and compared between diabetic and non-diabetic participants. The differences among age and ethnicity groups were explored. Results: A total of 6381 US adults (>50 years) were involved. The overall prevalence of sarcopenia was 17.8% for US elders, and the prevalence was higher (27.9% vs. 15.7%) in those with diabetes ones than those without. Stepwise regression revealed that sarcopenia was significantly associated with DM (Adjusted odds ratio=1.37, 95%CI: 1.08-1.22; P<0.05) after controlling for potential confounders including gender, age, ethnicity, educational level, BMI and muscle strengthening activity. A slightly fluctuate but overall increasing trend of sarcopenia prevalence was observed among diabetic elders while no obvious changing trend was observed in their counterparts in recent decades. Conclusion: Diabetic US older adults face significantly higher risk of sarcopenia when compared with their non-diabetic counterparts. Gender, age, ethnicity, educational level and obesity were important influencing factors of sarcopenia development.

引言
现有研究提示，肌肉减少症（sarcopenia）可能是糖尿病（diabetes mellitus, DM）的重要共病。然而，采用全国代表性数据开展的相关研究较为匮乏，肌肉减少症患病率随时间的变化趋势也尚未明确。为此，本研究旨在估算并比较美国老年糖尿病患者与非糖尿病患者的肌肉减少症患病率，同时探讨肌肉减少症的潜在预测因子，以及近数十年来该病的流行趋势。
方法
本研究数据提取自国家健康与营养检查调查（National Health and Nutrition Examination Survey, NHANES）。肌肉减少症与糖尿病均按照相应诊断标准进行定义。计算加权患病率，并对糖尿病参与者与非糖尿病参与者的加权患病率进行比较，同时分析不同年龄组与种族组间的患病率差异。
结果
本研究共纳入6381名50岁以上的美国成年人。美国老年人群的肌肉减少症总体患病率为17.8%，其中糖尿病患者的患病率（27.9%）显著高于非糖尿病患者（15.7%）。逐步回归分析显示，在控制性别、年龄、种族、教育水平、体重指数（BMI）和肌肉强化活动等潜在混杂因素后，肌肉减少症与糖尿病存在显著关联（校正后比值比=1.37，95%置信区间：1.08~1.22；P<0.05）。近数十年来，糖尿病老年患者的肌肉减少症患病率呈现小幅波动但总体上升的趋势，而非糖尿病老年患者则未观察到明显的变化趋势。
结论
与非糖尿病老年人群相比，美国老年糖尿病患者的肌肉减少症患病风险显著更高。性别、年龄、种族、教育水平与肥胖是肌肉减少症发生的重要影响因素。