Health inequalities across the trajectory of early-onset type 2 diabetes: a Scotland–Sweden study

Background

Early-onset type 2 diabetes mellitus (T2DM; diagnosed before 40 years of age) is an increasing public health problem.¹ It is particularly concerning because people who develop T2DM at younger ages have a more aggressive disease course, with earlier microvascular and cardiovascular complications and increased premature mortality compared with those diagnosed later.² Data from the 2024 Scottish Diabetes Survey indicates that nearly 10,000 people living with T2DM in Scotland are aged under 40 years .³

Early-onset T2DM is strongly socially patterned, with the highest incidence among people with lower socioeconomic position and from minority ethnic backgrounds. However, important knowledge gaps remain. Most studies have examined sociodemographic factors separately, and we know little about how these factors intersect to identify groups at particularly high risk. There is also limited evidence on inequalities after diagnosis: whether people from disadvantaged or minority backgrounds have a greater risk of vascular complications and premature mortality, and to what extent differences in clinical characteristics and pre-existing mental and physical multimorbidity contribute to these inequalities. Identifying which groups are at greatest risk of poor outcomes, and why, is important for targeting prevention and care.

Women with early-onset T2DM are of particular concern; recent Swedish data show a particularly rapid among young women. This is important because T2DM increasingly affects women during reproductive years, and pre-existing T2DM is associated with adverse pregnancy and neonatal outcomes. However, little is known about socioeconomic and ethnic inequalities in these outcomes, or whether subgroups with early-onset T2DM are particularly vulnerable.

This cross-country study will use population-wide linked data from Scotland and Sweden to investigate health inequalities across the trajectory of early-onset T2DM, from disease development to long-term complications and pregnancy outcomes. By combining sociodemographic and clinical information, we will identify high-risk subgroups and assess whether patterns are consistent across both settings. Findings will inform prevention, surveillance and care.

Aims

1. Identify sociodemographic groups at highest risk of early-onset T2DM in Scotland and Sweden by examining incidence according to age, sex, ethnicity/migration background and socioeconomic position, including how these factors intersect.
2. Determine inequalities in prognosis following early-onset T2DM, including microvascular and macrovascular complications and mortality, and assess the contribution of clinical characteristics and mental and physical multimorbidity.
3. Investigate socioeconomic and ethnic inequalities in pregnancy and neonatal outcomes among women with early-onset T2DM, including preeclampsia, preterm birth, stillbirth, major congenital anomalies and abnormal foetal growth.

Training outcomes

This PhD will provide the student with a unique skill-set encompassing epidemiology, advanced statistics and the use of large, complex linked data in research, with application to health inequalities in early-onset T2DM, an emerging major public health problem. The project includes an international exchange, allowing the PhD student to visit Karolinska Institute in Stockholm to work with Swedish data. The student will gain valuable experience interacting with academic, clinical and public health practice/policy colleagues, including through links with the NIHR Health Inequalities cardiovascular disease Consortium. They will engage in PPIE activities through established links with relevant PPIE groups within the University of Edinburgh supervisory team. This will provide broad experience of interdisciplinary and international collaboration and develop transferable skills important for their future career.

We will work with the student to develop a tailored training plan focused on health informatics and quantitative research. This will include training in R, routine data management and preparation, statistical methods including regression and survival modelling, causal inference, methods for studying intersectionality, and PPIE. The student will benefit from training in generic research and transferable skills and will be expected and supported to present their work to lay and professional audiences, and to submit articles to international peer-reviewed journals.

References

1. Luk A, Wild SH, Jones S, Anjana RM, Hivert MF, McCaffrey J, Gregg EW, Misra S. Early-onset type 2 diabetes: the next major diabetes transition. Lancet. 2025 Jun 28;405(10497):2313-2326. doi: 10.1016/S0140-6736(25)00830-X. Epub 2025 Jun 23. Erratum in: Lancet. 2025 Oct 11;406(10512):1564. doi: 10.1016/S0140-6736(25)02057-4. Erratum in: Lancet Neurol. 2026 May;25(5):e11. doi: 10.1016/S1474-4422(26)00121-3. PMID: 40570862.
2. Magliano, D.J., Sacre, J.W., Harding, J.L. et al. Young-onset type 2 diabetes mellitus — implications for morbidity and mortality. Nat Rev Endocrinol 16, 321–331 (2020). https://doi.org/10.1038/s41574-020-0334-z
3. Scottish Diabetes Group. Scottish Diabetes Survey 2024. NHS Scotland https://www.diabetesinscotland.org.uk/wp-content/uploads/2025/12/Scottish-Diabetes-Survey-2024.pdf
4. Carlsson S, Andersson T, Jansson S, Nyström T, Rolandsson O, Wei Y. Increasing incidence of early-onset type 2 diabetes in Sweden 2006-2021. Eur J Public Health. 2025 Dec 1;35(6):1258-1263. doi: 10.1093/eurpub/ckaf114. PMID: 40633064; PMCID: PMC12707497.