Approximately 60 000 people in England have coexisting type 2 diabetes mellitus (T2DM) and severe mental illness (SMI). They are more likely to have poorer health outcomes and require more complex care pathways compared with those with T2DM alone. Despite increasing prevalence, little is known about the healthcare resource use and costs for people with both conditions.

To assess the impact of SMI on healthcare resource use and service costs for adults with T2DM, and explore the predictors of healthcare costs and lifetime costs for people with both conditions.

This was a matched-cohort study using data from the Clinical Practice Research Datalink linked to Hospital Episode Statistics for 1620 people with comorbid SMI and T2DM and 4763 people with T2DM alone. Generalised linear models and the Bang and Tsiatis method were used to explore cost predictors and mean lifetime costs respectively.

There were higher average annual costs for people with T2DM and SMI (£1930 higher) than people with T2DM alone, driven primarily by mental health and non-mental health-related hospital admissions. Key predictors of higher total costs were older age, comorbid hypertension, use of antidepressants, use of first-generation antipsychotics, and increased duration of living with both conditions. Expected lifetime costs were approximately £35 000 per person with both SMI and T2DM. Extrapolating nationally, this would generate total annual costs to the National Health Service of around £250 m per year.

Our estimates of resource use and costs for people with both T2DM and SMI will aid policymakers and commissioners in service planning and resource allocation.

在英格兰，大约有 60 000 人同时患有 2 型糖尿病 (T2DM) 和严重精神疾病 (SMI)。与仅患有 T2DM 的人相比，他们更有可能有更差的健康结果，并且需要更复杂的护理途径。尽管患病率越来越高，但对这两种情况的人的医疗资源使用和成本知之甚少。

评估 SMI 对患有 T2DM 的成年人的医疗资源使用和服务成本的影响，并探索这两种疾病患者的医疗成本和终生成本的预测因素。

这是一项匹配队列研究，使用来自临床实践研究数据链的数据，该数据与医院事件统计相关，针对 1620 名 SMI 和 T2DM 共病患者和 4763 名 T2DM 患者。广义线性模型和 Bang 和 Tsiatis 方法分别用于探索成本预测因子和平均生命周期成本。

T2DM 和 SMI 患者的年平均费用（高出 1930 英镑）高于仅患有 T2DM 的人，这主要是由心理健康和非心理健康相关的住院费用驱动的。总成本较高的关键预测因素是年龄较大、合并高血压、使用抗抑郁药、使用第一代抗精神病药以及在这两种情况下的生存时间延长。SMI 和 T2DM 的预期终生成本约为每人 35 000 英镑。在全国范围内推算，这将为国家卫生服务局带来每年约 2.5 亿英镑的总成本。

我们对 T2DM 和 SMI 患者的资源使用和成本的估计将有助于决策者和专员进行服务规划和资源分配。