AIMS/HYPOTHESIS Obesity is a risk factor for type 2 diabetes, yet little is known about how timing and cumulative exposure of obesity are related to disease risk. The aim of this study was to examine the associations between BMI trajectories, age of onset of obesity and obese-years (a product of degree and duration of obesity) over early adulthood and subsequent risk of type 2 diabetes. METHODS Women aged 18-23 years at baseline (n = 11,192) enrolled in the Australian Longitudinal Study on Women's Health (ALSWH) in 1996 were followed up about every 3 years via surveys for up to 19 years. Self-reported weights were collected up to seven times. Incident type 2 diabetes was self-reported. A growth mixture model was used to identify distinct BMI trajectories over the early adult life course. Cox proportional hazards regression models were used to examine the associations between trajectories and risk of diabetes. RESULTS One hundred and sixty-two (1.5%) women were newly diagnosed with type 2 diabetes during a mean of 16 years of follow-up. Six distinct BMI trajectories were identified, varying by different initial BMI and different slopes of increase. Initial BMI was positively associated with risk of diabetes. We also observed that age at onset of obesity was negatively associated with risk of diabetes (HR 0.87 [95% CI 0.79, 0.96] per 1 year increment), and number of obese-years was positively associated with diabetes (p for trend <0.0001). CONCLUSIONS/INTERPRETATION Our data revealed the importance of timing of obesity, and cumulative exposure to obesity in the development of type 2 diabetes in young women, suggesting that preventing or delaying the onset of obesity and reducing cumulative exposure to obesity may substantially lower the risk of developing diabetes.

中文翻译：

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肥胖的发病年龄，成年早期的累积肥胖暴露和2型糖尿病的风险。

目的/假设肥胖是2型糖尿病的危险因素，但对于肥胖的发生时间和累积暴露与疾病风险之间的关系知之甚少。这项研究的目的是检查成年早期的BMI轨迹，肥胖发作年龄和肥胖年限（肥胖程度和持续时间的乘积）与随后的2型糖尿病风险之间的关系。方法1996年参加澳大利亚妇女健康纵向研究（ALSWH）的基线年龄为18-23岁的女性（n = 11,192），大约每3年进行一次随访，随访时间长达19年。自我报告的重量最多收集了7次。自行报告了2型糖尿病事件。使用生长混合物模型来识别成年人早期生命历程中不同的BMI轨迹。使用Cox比例风险回归模型检查轨迹与糖尿病风险之间的关联。结果在平均16年的随访中，有162名（1.5％）妇女被新诊断出患有2型糖尿病。确定了六种不同的BMI轨迹，它们随初始BMI的不同和上升斜率的不同而变化。最初的BMI与患糖尿病的风险呈正相关。我们还观察到，肥胖发病年龄与糖尿病风险呈负相关（每增加1年HR 0.87 [95％CI 0.79，0.96]），肥胖年数与糖尿病呈正相关（趋势<0.0001的p ）。结论/解释我们的数据揭示了肥胖时机和肥胖累积累积对年轻女性2型糖尿病发展的重要性，