Healthy aging refers to functional ability that enables well-being in older individuals. The focus thus shifts from chronological age to functional capacity and the individual's own experience of well-being. Type 1 diabetes is a chronic condition characterized by elevated blood glucose levels, which increases the risk of cardiovascular diseases and premature death. However, the life expectancy of individuals with type 1 diabetes has significantly improved due to advances in diabetes care.

There is limited research on aging with type 1 diabetes, and this study is at the forefront of addressing this gap by examining aging-and especially healthy aging-in type 1 diabetes from multiple perspectives. The goals are to investigate how individuals with type 1 diabetes age and what their functional capacity is compared to individuals without insulin-treated diabetes. The other aim is to identify factors in midlife that predict healthy aging in people with type 1 diabetes.

Ageing with type 1 diabetes is an emerging challenge due to improved life-expectancy of people with type 1 diabetes. While those who survive to an older age are considered survivors, the many years with type 1 diabetes and the chronic dysglycaemia inevitably also has negative health impacts on people living with this chronic disease. With scarce research in this area, ageing in type 1 diabetes has been identified as a research gap.

With this study, the aim is to assess the impact of ageing in people with type 1 diabetes via thorough characterization of older adults with type 1 diabetes, in comparison to matched controls. This will be accomplished through a comprehensive assessment of the participants' metabolic profile, body composition, vascular health, autonomic function, and a geriatric assessment focusing on the functional ability of the participants. In addition, this study will assess what type of challenges older adults with type 1 diabetes face regarding self-management, diabetes care, and daily life.

This study is a sub-study of the national Finnish Diabetic Nephropathy Study, initiated in 1997 and including adults with type 1 diabetes. Individuals over 65 living in the Helsinki capital area will now be invited for a regular FinnDiane study visit, as well as an additional visit for a geriatric assessment. The aim is to study 300 FinnDiane study participants and recruit a minimum of 100 matched controls. This cohort will be prospectively followed with a revisit after three to five years.

Inclusion Criteria:

• Participants of the Finnish Diabetic Nephropathy Study
• Type 1 diabetes
• With age above 65 years
• Informed consent provided

Exclusion Criteria:

• Age below 65 years

Participants of the Finnish Diabetic Nephropathy (FinnDiane) Study living in the Helsinki capital area. Controls will be recruited from spouses to match for sex and socioeconomic factors.

Individual-level data for the study participants are not publicly available because of the restrictions due to the study consent provided by the participant at the time of data collection. Researchers may propose collaboration to research the individual level data with correspondence with the lead investigator.