The FinnDiane LifeOne Study is a prospective observational cohort study protocol designed to assess how individuals with type 1 diabetes age and to identify factors that contribute to their healthy ageing, intrinsic capacity and its domains.
Key Findings
Background
Life expectancy for people with type 1 diabetes has increased due to improved treatment of diabetes and its comorbidities, allowing many to reach old age.
Despite increased longevity, knowledge of how individuals with type 1 diabetes age remains lacking.
Those who reach older age can be considered survivors, but their long-standing diabetes might still exhibit negative impacts on health and functional ability.
This gap in knowledge motivates the creation of the FinnDiane LifeOne Study.
Background
The WHO has shifted focus from chronological age to functional ability as the priority framework for healthy ageing this decade.
Functional ability reflects the ability of individuals to perform meaningful activities.
Functional ability is shaped by intrinsic capacity, the environment, and their interaction.
Intrinsic capacity encompasses five main domains: cognition, vitality, sensory function, locomotion, and psychological domain.
Healthy ageing is identified as the WHO's priority for this decade.
Methods
The FinnDiane LifeOne Study is designed as a prospective observational cohort study recruiting older adults with type 1 diabetes and matched controls.
The study aims to recruit a minimum of 300 individuals with type 1 diabetes from the existing FinnDiane Study, aged over 65 years.
A minimum of 100 matched controls without insulin-dependent diabetes will also be recruited.
Participants will be comprehensively characterised including clinical assessment, laboratory tests, questionnaires, and geriatric assessment of different aspects of functioning ability.
Follow-up assessments are planned at 5-year intervals.
The study is registered as NCT07289204 and approved by the Ethics Committee of HUS Helsinki University Hospital (HUS/4387/2023).
Methods
The study will compare ageing outcomes between individuals with type 1 diabetes and matched controls without insulin-dependent diabetes.
Comparisons will be made across intrinsic capacity domains: cognition, vitality, sensory function, locomotion, and psychological domain.
For those with type 1 diabetes, the study will further assess which factors from the FinnDiane baseline and trajectories during follow-up predict healthy ageing in individuals aged above 65.
The dual comparison design allows identification of diabetes-specific impacts on ageing beyond general ageing effects.
Background
People with type 1 diabetes aged over 65 are identified as a vulnerable group whose ageing trajectory and contributing factors to healthy ageing remain poorly understood.
The study explicitly frames older adults with type 1 diabetes as a vulnerable population.
The tension is noted between their status as 'survivors' who have lived long with diabetes and the potential long-term negative impacts of diabetes on health and functional ability.
The study aims to identify factors that contribute to healthy ageing, intrinsic capacity, and its domains specifically within this group.
Findings will be published in international peer-reviewed journals with an open access choice.
What This Means
This paper describes the design and protocol for a new research study called the FinnDiane LifeOne Study, which will follow older adults with type 1 diabetes to understand how they age compared to people without diabetes. As medical care has improved, many people with type 1 diabetes are now living into their 60s, 70s, and beyond — a group that has historically been understudied. The researchers want to understand whether aging with decades of type 1 diabetes leads to different health and functional outcomes compared to the general population, and what factors might help or hinder healthy aging in this group.
The study will recruit at least 300 people with type 1 diabetes over age 65 and at least 100 people without insulin-dependent diabetes for comparison. Participants will undergo comprehensive evaluations every five years, including clinical tests, lab work, questionnaires, and assessments of physical, cognitive, sensory, and psychological functioning. The researchers are using a framework promoted by the World Health Organization that focuses on 'intrinsic capacity' — a person's overall mental and physical abilities — rather than just age or disease diagnoses alone.
This research suggests that understanding how long-term type 1 diabetes interacts with normal aging processes could help identify who is at greatest risk for declining function and who manages to age well despite their condition. Because this is a protocol paper, no results are yet available, but the study is designed to generate evidence that could eventually inform better care and support for an aging population living with type 1 diabetes.
Nicklén J, Satuli-Autere S, Rimpeläinen K, Dufva A, Ylinen A, Franzén E, et al.. (2026). FinnDiane LifeOne Study: influence of ageing on people with type 1 diabetes - a prospective observational cohort study protocol.. BMJ open. https://doi.org/10.1136/bmjopen-2026-122380