AIMS/HYPOTHESIS We assessed whether the risk of developing type 2 diabetes and the age of onset varied with the age at diabetes diagnosis of affected family members. METHODS We performed a national register-based open cohort study of individuals living in Denmark between 1995 and 2012. The population under study consisted of all individuals aged 30 years or older without diagnosed diabetes at the start date of the cohort (1 January 1995) and who had information about their parents' identity. Individuals who turned 30 years of age during the observation period and had available parental identity information were also added to the cohort from that date (open cohort design). These criteria restricted the study population mostly to people born between 1960 and 1982. Multivariable Poisson regression models adjusted for current age and highest educational attainment were used to estimate incidence rate ratios (IRRs) of type 2 diabetes. RESULTS We followed 2,000,552 individuals for a median of 14 years (24,034,059 person-years) and observed 76,633 new cases of type 2 diabetes. Compared with individuals of the same age and sex who did not have a parent or full sibling with diabetes, the highest risk of developing type 2 diabetes was observed in individuals with family members diagnosed at an early age. The IRR was progressively lower with a higher age at diabetes diagnosis in family members: 3.9 vs 1.4 for those with a parental age at diagnosis of 50 or 80 years, respectively; and 3.3 vs 2.0 for those with a full sibling's age at diagnosis of 30 or 60 years, respectively. CONCLUSIONS/INTERPRETATION People with a family member diagnosed with diabetes at an earlier age are more likely to develop diabetes and also to develop it at an earlier age than those with a family member diagnosed in later life. This finding highlights the importance of expanding our understanding of the interplay between genetic diabetes determinants and the social, behavioural and environmental diabetes determinants that track in families across generations. Accurate registration of age at diagnosis should form an integral part of recording a diabetes family history, as it provides easily obtainable and highly relevant detail that may improve identification of individuals at increased risk of younger onset of type 2 diabetes. In particular, these individuals may benefit from closer risk factor assessment and follow-up, as well as prevention strategies that may involve the family.

中文翻译：

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家族性糖尿病的状况和诊断时的年龄对2型糖尿病风险的影响：丹麦一项基于全国登记的研究。

目的/假设我们评估了罹患2型糖尿病的风险和发病年龄是否随患病家庭成员诊断为糖尿病的年龄而变化。方法我们对1995年至2012年间居住在丹麦的个人进行了基于国家注册的开放队列研究。研究对象包括队列开始日期（1995年1月1日）和30岁以上且未诊断出糖尿病的所有个体，以及知道父母身份的人。在观察期内年满30岁并具有可用父母身份信息的人也将从该日期开始添加到该队列中（开放队列设计）。这些标准将研究人群主要限制在1960年至1982年之间出生的人群。使用针对当前年龄和最高学历进行调整的多变量Poisson回归模型来估计2型糖尿病的发生率（IRR）。结果我们随访了2,000,552名个体，平均年龄为14年（24,034,059人年），观察到76,633例新的2型糖尿病病例。与没有父母或全兄弟姐妹的同年龄和性别的人相比，在被诊断为家庭成员的人中，发现其罹患2型糖尿病的风险最高。在家庭中，糖尿病患者的IRR随着年龄的增加而逐渐降低：父母年龄在50岁或80岁的患者的IRR分别为3.9％和1.4％；兄弟姐妹被诊断为30岁或60岁的年龄分别为3.3和2.0。结论/解释与家庭成员诊断较晚的人相比，家庭成员诊断较早的人患糖尿病的可能性更高。这一发现凸显了扩大我们对遗传糖尿病决定因素与世代相传的家庭中社会，行为和环境糖尿病决定因素之间相互作用的理解的重要性。在诊断时准确记录年龄应成为记录糖尿病家族史的重要组成部分，因为它提供了易于获得且高度相关的详细信息，可以改善对2型糖尿病年轻发作风险增加的个体的识别。特别是，这些人可能会受益于更严格的风险因素评估和跟进，