Objective Diabetes is a risk factor for dementia but little is known about the impact of diabetes duration on the risk of dementia. We investigated the effect of type 2 diabetes duration on the risk of dementia. Design Prospective cohort study using health claims data representative for the older German population. The data contain information about diagnoses and medical prescriptions from the in- and outpatient sector. Methods We performed piecewise exponential models with a linear and a quadratic term for time since first type 2 diabetes diagnosis to predict the dementia risk in a sample of 13,761 subjects (2,558 dementia cases) older than 65 years. We controlled for severity of diabetes using the Adopted Diabetes Complications Severity Index. Results We found a U-shaped dementia risk over time. After type 2 diabetes diagnosis the dementia risk decreased (26% after 1 year) and reached a minimum at 4.75 years, followed by an increase through the end of follow-up. The pattern was consistent over different treatment groups, with the strongest U-shape for insulin treatment and for those with diabetes complications at the time of diabetes diagnosis. Conclusions We identified a non-linear association of type 2 diabetes duration and the risk of dementia. Physicians should closely monitor cognitive function in diabetic patients beyond the first few years after diagnosis, because the later increase in dementia occurred in all treatment groups.

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糖尿病病程和痴呆风险：基于德国健康声明数据的队列研究

目的 糖尿病是痴呆的危险因素，但对于糖尿病病程对痴呆风险的影响知之甚少。我们调查了 2 型糖尿病病程对痴呆风险的影响。使用代表德国老年人口的健康声明数据设计前瞻性队列研究。这些数据包含有关住院和门诊部门的诊断和医疗处方的信息。方法 我们对自首次诊断 2 型糖尿病以来的时间进行了具有线性和二次项的分段指数模型，以预测 65 岁以上的 13,761 名受试者（2,558 例痴呆病例）样本中的痴呆风险。我们使用采用的糖尿病并发症严重程度指数来控制糖尿病的严重程度。结果 我们发现随着时间的推移存在 U 型痴呆风险。诊断出 2 型糖尿病后，痴呆风险降低（1 年后 26%）并在 4.75 年达到最低值，随后在随访结束时增加。这种模式在不同的治疗组中是一致的，胰岛素治疗和糖尿病诊断时糖尿病并发症的 U 型最强。结论 我们确定了 2 型糖尿病病程与痴呆风险之间的非线性关联。医生应在糖尿病患者确诊后的最初几年后密切监测认知功能，因为所有治疗组都发生了痴呆症的后期增加。具有最强的 U 形用于胰岛素治疗和糖尿病诊断时患有糖尿病并发症的人。结论 我们确定了 2 型糖尿病病程与痴呆风险之间的非线性关联。医生应在糖尿病患者确诊后的最初几年后密切监测认知功能，因为所有治疗组都发生了痴呆症的后期增加。具有最强的 U 形用于胰岛素治疗和糖尿病诊断时患有糖尿病并发症的人。结论 我们确定了 2 型糖尿病病程与痴呆风险之间的非线性关联。医生应在糖尿病患者确诊后的最初几年后密切监测认知功能，因为所有治疗组都发生了痴呆症的后期增加。