Department of Epidemiology, Erasmus Medical Center, University Medical Center, Rotterdam, Netherlands.
J Clin Endocrinol Metab. 2018 Mar 1;103(3):946-955. doi: 10.1210/jc.2017-01921.
There are discrepancies in the seasonality of insulin resistance (IR) across the literature, probably due to age-related differences in the seasonality of lifestyle factors and thermoregulation mechanisms.
To estimate the seasonality of IR according to the homeostatic model assessment-IR (HOMA-IR), glucose, and insulin levels and to examine the role of lifestyle markers [body mass index (BMI) and physical activity] and meteorological factors, according to age.
DESIGN, SETTING, AND PARTICIPANTS: Seasonality was examined using cosinor analysis among middle-aged (45 to 65 years) and elderly (≥65 years) participants of a population-based Dutch cohort. We analyzed 13,622 observations from 8979 participants (57.6% women) without diagnosis of diabetes and fasting glucose <7 mmol/L. BMI was measured, physical activity was evaluated using a validated questionnaire, and meteorological factors (daily mean ambient temperature, mean relative humidity, total sunlight hours, and total precipitation) were obtained from local records. Seasonality estimates were adjusted for confounders.
Among the middle-aged participants, seasonal variation estimates were: 0.11 units (95% confidence interval: 0.03, 0.20) for HOMA-IR, 0.28 µIU/mL (-0.05, 0.69) for insulin, and 0.05 mmol/L (0.01, 0.09) for glucose. These had a summer peak, and lifestyle markers explained the pattern. Among the elderly, seasonal variations were: 0.29 units (0.21, 0.37) for HOMA-IR, 0.96 µIU/mL (0.58, 1.28) for insulin, and 0.01 mmol/L (-0.01, 0.05) for glucose. These had a winter peak and ambient temperature explained the pattern.
Impaired thermoregulation mechanisms could explain the winter peak of IR among elderly people without diabetes. The seasonality of lifestyle factors may explain the seasonality of glucose.
胰岛素抵抗（IR）在文献中的季节性存在差异，这可能是由于与年龄相关的生活方式因素和体温调节机制的季节性差异所致。
根据稳态模型评估-IR（HOMA-IR）、血糖和胰岛素水平来估计 IR 的季节性，并根据年龄检查生活方式标志物（体重指数 [BMI] 和身体活动）和气象因素的作用。
设计、地点和参与者：在一项基于人群的荷兰队列中，对中年（45 至 65 岁）和老年（≥65 岁）参与者使用余弦分析来检查季节性。我们分析了来自 8979 名参与者（57.6%为女性）的 13622 个观察值，这些参与者没有糖尿病诊断，且空腹血糖<7mmol/L。测量了 BMI，使用经过验证的问卷评估了身体活动，从当地记录中获得了气象因素（每日平均环境温度、平均相对湿度、总阳光小时数和总降水量）。季节性估计值经过混杂因素调整。
在中年参与者中，季节性变化估计值为：HOMA-IR 为 0.11 单位（95%置信区间：0.03，0.20），胰岛素为 0.28µIU/mL（-0.05，0.69），血糖为 0.05mmol/L（0.01，0.09）。这些指标都有夏季高峰，生活方式标志物解释了这种模式。在老年人中，季节性变化为：HOMA-IR 为 0.29 单位（0.21，0.37），胰岛素为 0.96µIU/mL（0.58，1.28），血糖为 0.01mmol/L（-0.01，0.05）。这些指标都有冬季高峰，环境温度解释了这种模式。
体温调节机制受损可能解释了无糖尿病老年人中 IR 的冬季高峰。生活方式因素的季节性可能解释了血糖的季节性。
