Experiences of adults with adult-onset type 1 diabetes: a cross-sectional study

Introduction

Type 1 diabetes (T1D) is an autoimmune condition where the pancreas does not produce enough insulin (World Health Organization 2021). Without insulin, the body cannot turn glucose into energy. Without this energy, the body burns its own fats, releasing ketone bodies into the blood. This process can lead to diabetic ketoacidosis, a life-threatening condition that can lead to coma and death (Evans 2019). Individuals living with T1D face a lifetime of managing the disease through insulin injections or use of an insulin pump, monitoring of blood glucose levels, and following diet and exercise plans (Chiang et al. 2014).

According to the most recent National Health Survey data, an estimated 1.2 million Australians (4.9% of the population) had diabetes – including T1D, type 2 diabetes (T2D), and type unknown – in 2017–18 (Australian Bureau of Statistics 2018). The most recent data from the National (insulin-treated) Diabetes Register (NDR) listed 2800 new diagnoses of T1D in Australia in 2018 (Australian Institute of Health and Welfare 2018). These figures are only growing: in September 2021, there were >1.4 million people with diabetes (5.4% of the population) registered with the Australian Government Initiative, National Diabetes Services Scheme (National Diabetes Services Scheme: An Australian Government Initiative 2021). Diabetes costs the Australian healthcare system billions of dollars each year; in 2018, diabetes expenditure reached A$2.7 billion, up from A$1.2 billion in 2009 (Australian Institute of Health and Welfare 2020a). Preventable diabetes-related hospitalisations and complications also cost the Australian healthcare system an extra A$32 000 per patient, each year (Diabetes NSW & ACT 2021).

There is a common misconception that T1D is a childhood disease. Although many cases do present in childhood, up to half of all T1D cases present in adulthood. In 2018, 49% of T1D diagnoses in Australia were identified in adults aged >20 years (Australian Institute of Health and Welfare 2020b). Emerging evidence suggests that many adults with T1D are initially misdiagnosed, increasing the risk for diabetic ketoacidosis and poorer long-term physical and mental health outcomes (Muñoz et al. 2019; Thomas et al. 2019).

Although there is some academic literature that examines adult-onset T1D, the majority of the research literature has focused on childhood onset of T1D (Fourlanos et al. 2005; Davis et al. 2018). Although the needs of adults with T1D were first added to the Australian Evidence-Based Clinical Guidelines for Diabetes in 2011 (Craig et al. 2011), the information primarily focuses on the transition from paediatric to adult care. Given that T1D is a lifelong disease and burdensome on both the patient and the healthcare system, it is essential that the Australian health system is appropriately resourced to provide best practice care to adults presenting with T1D. Therefore, the aim of this study was to examine the experiences of individuals living with adult-onset T1D in relation to their diagnosis experience, access to health care, and post-diagnostic wellbeing.

Methods

Results

Over the 7-week data collection period, 150 potential participants expressed interest in the survey. Eleven did not complete the eligibility criteria questions, nine did not meet inclusion criteria, five recorded responses were removed based on duplicate IP addresses, and five had >30% missing data. Overall, data from 120 participants were included in the final analysis.

Discussion

Traditionally considered a childhood disease, half of all T1D diagnoses occur in adults aged ≥20 years (Thomas et al. 2019). This study aimed to examine the experiences of individuals diagnosed with T1D in adulthood, with particular focus on individual characteristics and family and personal health history, diagnosis experience, access to care, and post-diagnostic wellbeing. High misdiagnosis rates, and moderate-to-high levels of anxiety and diabetes-related distress, were prominent in this sample.

Among the participants there were several cases of polyautoimmunity, which is the presence of two or more autoimmune conditions in a single patient (Anaya 2014). One-third of the sample had an additional autoimmune disease to their T1D. These findings contribute an adult perspective to the well-researched comorbidity of autoimmune conditions among children with T1D. For example, out of a cohort of 25 759 children and adults on the US T1D Exchange Clinical Network Registry, it was found that >25% of individuals had at least one additional autoimmune condition (Hughes et al. 2016). A separate study of 491 children in the US with T1D found that one-third had an additional autoimmune condition (Triolo et al. 2011). In Australia, research with 102 Australians diagnosed with T1D in adulthood found that one-quarter had polyautoimmunity (Fourlanos et al. 2006). In addition to living with a comorbid autoimmune condition, one-third of our participants reported a family history of autoimmune disease. The presence of both polyautoimmunity, and a family history of autoimmune conditions, is well established in the paediatric T1D literature (Alhonen et al. 2011; Parkkola et al. 2013; Turtinen et al. 2019). Our findings suggest that the same diagnostic criteria may be applicable to adults presenting with T1D symptoms.

For more than one-third of participants, misdiagnosis was a key part of their T1D diagnosis experience. Of those misdiagnosed, the majority received an incorrect T2D diagnosis. This finding is remarkably consistent with two other cross-sectional studies involving adults with T1D. A US study involving 856 participants with adult-onset T1D found that 39% had been initially misdiagnosed; of the 39%, over three-quarters were misdiagnosed with T2D (Muñoz et al. 2019). Similarly, a UK study with 583 adults with T1D (age of onset <30 years) found that 38% did not start insulin therapy at diagnosis, and were treated as T2D patients (Thomas et al. 2019). Our findings contribute to a small, but growing body of literature characterising misdiagnosis rates among adults with T1D (Leslie et al. 2021), and is the first demonstrating this phenomenon in Australia. Misdiagnosis has implications for patient wellbeing: it can create a sense of distrust towards health professionals and healthcare systems, leading to delays in treatment and long-term physical and psychological complications (Shepherd 2008; Bao et al. 2019). This was also evident among our sample, some of whom reported intentionally avoiding T1D medical appointments due to dissatisfaction with past healthcare experiences.

In the past 12 months, the majority of participants reported visiting an endocrinologist, optometrist, and diabetes educator. Fewer participants reported seeing other types of allied health services, such as a podiatrist, dietitian, or mental health professional. T1D management requires a multidisciplinary care team, and evidence suggests that consistently accessing allied health services, in addition to medical appointments, optimises outcomes in this patient population (Wiley et al. 2015). The most recent National Evidence-Based Clinical Care Guidelines for Type 1 Diabetes in Children, Adolescents and Adults states that people with T1D should be seeing a dietitian for comprehensive education in accurate carbohydrate counting and matching insulin to carbohydrates, and that podiatrists play an important role in preventing T1D-attributable foot complications (Craig et al. 2011). Evidence suggests that the absence of allied health services as part of routine T1D care can result in generally poorer diabetes management, and can lead to long-term T1D complications such as retinopathy, neuropathy, and cardiovascular disease (Saleh 2015; Litchfield et al. 2019). This also places financial strain on the Australian healthcare system: the average annual cost per T1D patient increases from A$3468 for individuals without complications, to AUD 32 000 for individuals with micro and macrovascular complications (Diabetes NSW & ACT 2021).

Participants overall reported elevated levels of distress on the T1-DDS. These findings complement US-based cross-sectional studies utilising the T1-DDS, demonstrating the global impact of T1D (Polonsky et al. 2016; Abdoli et al. 2020). The T1-DDS includes seven subscales, one of which is management distress: a sense of disappointment in one’s effort to control their diabetes (Fisher et al. 2015). In the current study, participants scored highest (3.0) for the management distress category. Some management techniques have been shown to reduce T1D distress, including use of insulin pumps as an alternative to manual injections. The most recent Australian data (albeit from 2014) states that only 12% of adults with T1D are insulin pump users, with cost being the biggest barrier to higher uptake (Diabetes Australia 2014). Further, there are currently no specific recommendations for screening and treatment of diabetes distress under T1D clinical care guidelines. Based on our findings, this presents a clear gap in care, which should be filled as part of routine clinical care for T1D.

This study’s main strength is in its novelty, by exploring the experiences of Australians diagnosed with T1D as an adult. The multipronged recruitment strategy allowed for the recruitment of diverse participants across Australia. Although only descriptive, these findings provide a starting point for future research to improve the patient experience and delivery of health care to adults with T1D. Still, we acknowledge the research limitations. Our sample may not be representative of the broader Australian population with T1D: our sample was predominantly female, even though more males are diagnosed with T1D in adulthood than females. The self-reported nature of the survey also introduces potential recall and response bias; however, given participant anonymity, we expect that the effect of participants’ response bias was minimised. This survey was administered during the COVID-19 pandemic, which may have contributed excess diabetes-related distress, anxiety, and depression among participants. Although we did include COVID-19-related questions in our survey, we acknowledge that the pandemic itself may confound our findings. Finally, we were unable to calculate the participation rate of the survey, as the anonymous link was distributed among an unknown number of individuals through our diverse recruitment strategy.

Conclusion

This study has explored the experiences of adults diagnosed with T1D in Australia. Our findings contribute to a small, but growing body of literature focusing on adult diagnoses of T1D, which historically has been considered a childhood disease only. A number of areas of improvement in healthcare delivery were identified for this population, including improving patients’ diagnosis experience, and the introduction of regular screening for T1D-related distress. This research should be used as a starting point for more targeted research in the diabetes sphere.

Data availability

The data that support this study will be shared upon reasonable request to the corresponding author.

Conflicts of interest

The authors declare no conflicts of interest.

Declaration of funding

This research did not receive any specific funding.