The barriers and facilitators to managing diabetes with insulin in adults with intellectual disabilities: A systemised review of the literature

Abstract Background People with intellectual disabilities are more likely to have diabetes and develop complications from it. Diabetes management is complex and insulin treatment in particular, people with intellectual disabilities may require additional support that is not always available. This review aimed to identify barriers and facilitators to managing diabetes with insulin in adults with intellectual disabilities. Method Patient and public involvement (PPI) was integral to the development of the research question. A systemised review was conducted across CINAHL, the British Nursing Index and MEDLINE. PRISMA guidelines were followed. Narrative synthesis of the evidence was undertaken. Results Barriers and facilitators to managing diabetes with insulin in people with intellectual disabilities were identified related to the individual, other people participating in their care, and broader environmental and social factors. Conclusions People with intellectual disabilities who use insulin, require reasonable adjustments to education, support, and a person‐centred approach to facilitate supported self‐management. More training for their supporters is needed and further inclusive research with PPI is recommended.


| INTRODUCTION
In the United Kingdom, in 2019, there were 3.9 million people identified as having diabetes and it is estimated that a further million people have it, but have not been diagnosed yet (Diabetes UK, 2020).
According to the World Health Organisation, 422 million people worldwide have diabetes, with numbers estimated to rise to over half a billion by 2030 (WHO, 2021). Diabetes is characterised by raised blood glucose levels (hyperglycaemia) resulting from partial or total insufficiency in the insulin hormone (Egan & Dinneen, 2019). This serious long-term condition requires management to prevent health complications including cardiovascular disease, kidney disease, neuropathy, problems with the eyes and feet (Egan & Dinneen, 2019).
Compared with the general population, diabetes affects people with intellectual disabilities disproportionately, they have 2.46 times higher odds for developing diabetes, with 8.5% of people with intellectual disabilities having the condition (Vancampfort et al., 2022).
People with intellectual disabilities experience poorer health outcomes  and are at increased risk of developing diabetes complications due to healthcare inequalities (Hanlon et al., 2018;MacRae et al., 2015). There are higher rates of hospitalisation among people with intellectual disabilities, with evidence of barriers in accessing diabetes screening and health checks within primary care (Dunn et al., 2018;Hanlon et al., 2018). The World Health Organisation (WHO, 2012) identifies intellectual disabilities as an area for research priority and the NHS (2019) long-term plan includes improving understanding of the needs of people with disabilities and reducing inequalities in health. Issues of health inequality for people with intellectual disabilities have been further amplified by the COVID-19 pandemic (Williamson et al., 2021).
There are two main types of diabetes, both of which are more prevalent in people with intellectual disabilities (NHS Digital, 2019): type 1 accounts for about 8% of cases and type 2 approximately 90% (Diabetes UK, 2020). Insulin therapy is required for all people with type 1 and some with type 2 (Diabetes UK, 2020) and can be complex because it requires blood glucose monitoring, self-injections or insulin pump, dose adjustment, dietary considerations, and management of high or low blood glucose. There are safety issues around insulin therapy, placing it in the top high-alert medicines internationally (Cousins et al., 2011).
There is growing awareness of the importance of making reasonable adjustments to support people with intellectual disabilities to manage their diabetes (NHS Rightcare, 2017) and an increase in research focussing on these matters. However, some issues, including barriers and facilitators to diabetes management with insulin, need more attention because people with intellectual disabilities experience inequitable access to diabetes education and healthcare Smith & Phillips, 2018). Better understanding of these will help in developing interventions to support people with intellectual diabetes and diabetes and therefore improve their health outcomes.

| Review design
A systemised review design was used, with the review process following the principles of a systematic review but limited to published peer-reviewed academic literature and a narrative synthesis of findings (Grant & Booth, 2009). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed (Moher et al., 2009). The review protocol was written as a summative assignment by the lead reviewer as part of a module in Applied Research Methods at Oxford Brookes University.

| Patient and public involvement (PPI)
PPI was integral to developing the research question for this literature review (Brand et al., 2020). The lead author is a Senior Diabetes Specialist Nurse in an outpatient department and facilitated a PPI meeting in 2019 attended by people with intellectual disabilities and their supporters. The group discussed living with intellectual disabilities and diabetes. It was agreed that diabetes is a challenging condition to manage and even more so for people with intellectual disabilities using insulin. The group were strongly in favour of a research project to focus on this: '…help people out and find out new ways of doing this' (person with intellectual disability and diabetes).
'…a very much needed line of research for an area that doesn't receive enough attention' (sister of a person with Down's syndrome and diabetes).
'People with learning disabilities need a voice and help to manage their diabetes' (person with intellectual disability and diabetes).

| Developing the research question
An initial probe of the literature found that diabetes management in people with intellectual disabilities has been increasingly researched in recent years, but there is a lack of focus on how those using insulin manage their diabetes. Informed with the feedback from the PPI meeting, the research question was formed using the PEO question format (Munn et al., 2018); in adults with diabetes (population) and intellectual disabilities (exposure) what are the barriers and facilitators to managing diabetes with insulin (outcome)?

| Search strategy
There was consensus between the reviewers to search the following databases: Cumulative Index of Nursing and Allied Health Literature (CINAHL), the British Nursing Index and MEDLINE, as these were considered most relevant to the topic. The searches were conducted by the lead reviewer between December 2021 and January 2022. Support was sought from the university health librarian to ensure a robust search using appropriate key terms (Table 1). Reference lists of retrieved papers were checked manually by the lead reviewer. were appraised. During the appraisal process two papers were excluded based on low qualityone had no mention of ethical considerations, including consent, and the other did not include the results of the study. Two papers were excluded because they were not primary research, one paper was excluded because it was specific to people with cognitive impairment, such as dementia, rather than intellectual disability. Four papers were excluded as they were literature reviews. One paper was excluded as it was a guidance document.
Among included studies, a published and peer-reviewed service To explore repertoires of responsibility in accounts of managing diabetes for adults with intellectual disability.
Qualitative study. Semi-structured interviews of seven adults with intellectual disability and diabetes, and seven people who they nominated as supporting their diabetes management.
Critical discursive psychological approach to analysis.

New Zealand
The role of key workers in supporting people with intellectual disability in the selfmanagement of their diabetes: a qualitative New Zealand study.
To explore how key workers supported the self-management of diabetes in people with intellectual disability.
Qualitative study. Semi-structured interviews of 17 key workers (nominated by people with diabetes & intellectual disability and identified as having responsibility in facilitating primary healthcare access for the person). General Inductive Approach to thematic analysis. No (but they are in Hale et al., 2011, which is part of the same project) Medium (Continues) improvement project was included (Gregory, 2019) because it reported specifically on a project to improve service standards for people who are housebound requiring insulin. A total of 11 papers were included in this literature review, see Table 2.

| Data extraction
The lead reviewer used a tailored data extraction template designed by the reviewers to capture relevant information from the included papers (see Appendix S1). The information extracted included: the country and area of the study, the study setting, the aims and objectives, the participant population, whether the perspectives of people with intellectual disabilities were included, eligibility and recruitment, the methodology and study design, data collection method and analysis, barriers, and facilitators relevant to using insulin, relevant suggestions from the authors and anything else of interest. Throughout the data extraction process, each paper was double-checked by the second reviewer.

| Quality assessment
The papers were assessed for quality using the adapted Critical Appraisal Skill Programme (2018) (Appendix S1); all papers were assessed by both reviewers and high level of consensus reached.
Gregory (2019) was not quality assessed as a research paper because it was a service improvement project, so this was given low weighting in the data analysis process. Five papers were assessed as medium quality because there was a lack of examination of the researchers' own role and influence throughout the research process, for example, opportunity for participants to check the interview data, or discussion about the role of the researcher as a person without intellectual disability in relationship to the participants (Cardol et al., 2012a(Cardol et al., , 2012bPaterson et al., 2020;Rouse & Finlay, 2016;Trip et al., 2016). Five papers were assessed as high quality Dysch et al., 2012;Hale et al., 2011;Maine et al., 2017;Whitehead et al., 2016). To ensure the findings of the review were reliable, both reviewers conducted quality assessment and agreed on exclusion/ inclusion.   Hale et al. (2011), Maine et al. (2017, Rouse and Finlay (2016) and Whitehead et al. (2016). Paterson et al. (2020) interviewed carers about diabetes medication-taking but did not explain why the people with intellectual disabilities were not interviewed themselves.

| Data analysis
The data was analysed using a systematic and rigorous coding and themes development process, aiming to combine results from included studies (Aveyard, 2019). Papers were read by both reviewers.
The lead reviewer re-read papers and made reflective notes throughout the appraisal and analysis process as recommended by Aveyard

| RESULTS
There were three main themes, each with subthemes, related to the barriers and facilitators of managing diabetes with insulin in people with intellectual disabilities: if we just gave her support' (p. 794).

| Knowledge
A lack of understanding about diabetes, or inadequate access to diabetes education, was a barrier to managing diabetes with insulin Cardol et al., 2012a;Hale et al., 2011;Maine et al., 2017). Barriers to knowledge included a lack of accessible information or structured education for people with intellectual disabilities.
In contrast, if a person was supported to understand their condition, why they needed insulin and had access to information, this facilitated their diabetes management according to data from all of the papers except Gregory (2019) and Paterson et al. (2020). Maine et al. (2017) found that diabetes knowledge facilitated confidence and competence in self-management. For example, one of their participants enjoyed being expert in self-administering his insulin and having competence in blood glucose monitoring. Cardol et al. (2012b) Paterson et al. (2020) the two most common reasons for not taking prescribed medication were forgetting to take it and side effects. Brown et al. (2017) highlighted that a simplified insulin management plan is sometimes implemented for people with intellectual disabilities, leading to higher blood glucose levels and increased diabetes complications risk.
However, requiring insulin was not always perceived as negative.
A nurse in Cardol et al.'s (2012a) research expressed that they were more attentive towards a client who had diabetes and required insulin. Paterson et al. (2020) highlighted the importance of using insulin to optimise glycaemic levels and suggested that with support people with intellectual disabilities may reach comparable levels of medication-taking to those without intellectual disability.  (2017) found that autonomy for the person with diabetes was achieved through both the acceptance and rejection of support from others. Support was sometimes described as 'doing' in terms of physically injecting the insulin and checking the glucose  and other times it was about facilitating, encouraging, and enabling a person to be as independent as possible .

| Shared responsibility
Managing diabetes together and sharing responsibility was a facilita-

| Attitudes
The attitudes of other people acted as a barrier or a facilitator to being able to manage diabetes with insulin. This was apparent from data from seven of the studies Cardol et al., 2012a, 2012b, Maine et al., 2017, Rouse & Finlay, 2016Trip et al., 2016. Where there was a positive attitude from other people, this facilitated the person's self-management abilities. In

| Communication
The 3.2.8 | Conflict between protecting the person from harm versus facilitating their autonomy to selfmanage their diabetes This was a theme within all papers except for Cardol et al. (2012b) and Gregory (2019). Rouse and Finlay (2016) found contradictory ideas regarding diabetes management in that people with intellectual disabilities should have independence and freedom of choice, but that those who have responsibility for supporting them should limit these choices to protect them from risky decisions. Similarly, Trip et al. (2016) found that key workers sometimes felt like they were 'lifestyle police' in terms of managing the person's diabetes with them. Hale et al. (2011) explained that staff supporting individuals with intellectual disabilities to manage their diabetes, found it difficult to know how much assistance to provide, especially if the person appeared knowledgeable and confident. Whitehead et al. (2016) found that support workers referred to the balance between benefit and risk; supporting people to stay healthy and maintaining autonomy. For example, a person with intellectual disabilities for whom the decision was made that he required someone trained in hypo/hyperglycaemia management to escort him when he goes out.

| Reasonable adjustments and adaptations
The need for reasonable adjustments to facilitate diabetes management for people with intellectual disabilities who use insulin was a theme throughout the results, excluding Dysch et al. (2012). A flexible approach to care, resources and education that are adapted to the needs of people with learning disabilities and projects to improve support for people facilitated diabetes management Gregory, 2019). For example, being accompanied to a diabetes consultation was very much appreciated by people with intellectual disabilities in Cardol et al.'s (2012b) study because health information could be explained to them later on. Conversely, if there were inflexible services, a lack of adapted resources such as structured education or inadequate access to EasyRead material, this was a barrier to optimal diabetes management ).

| Person-centred care
Person-centred care was identified as a facilitator in five of the papers. This included the importance of seeing people as individuals and adapting to their requirements. For example, a psychologist in Brown et al.'s (2017) study expressed that people with intellectual disabilities and diabetes require tailored education and treatment packages to be fully informed and to achieve good health. However, time and resource limitations made it challenging to provide personcentred care .

| Structure of services
The way services were structured had an influence on how people managed their diabetes with insulin Gregory, 2019;Hale et al., 2011;Paterson et al., 2020;Trip et al., 2016). District nursing services regularly facilitate insulin administration but there are limitations  so an insulin regimen more than once a day can be challenging (even if it is appropriate). Furthermore, people with intellectual disabilities may find it restrictive having to wait at home for district nurses to come. In Whitehead et al.'s (2016) research, one participant did not want to be tied down to being at home for a second daily insulin visit from the nurse, although it may have improved her glycaemic levels. Gregory (2019) illustrated that there are creative ways of improving service standards for people who need support at home to manage their insulin, but her project required additional funding and as she points out, this can be challenging to sustain. Examples of positive working within services included multidisciplinary team working Trip et al., 2016), and the professionals in Brown et al.'s (2017) study advocated a shared care pathway between the diabetes and intellectual disabilities teams to enhance care.

| Where the person lives
Having access to support from family, carers, peers or healthcare professionals may vary depending on where a person lives. For example, in supported living there may be a worker to support with insulin management, or friends to provide support and encouragement (Maine et al., 2017 andWhitehead et al., 2016). However, Maine et al. (2017) and Cardol et al. (2012b) found that the social setting was sometimes detrimental to self-management, because of regimented routines, communal meals, and dietary temptations. For individuals living independently, some required daily visits from nurses to support with insulin administration (Hale et al., 2011). There were limitations on what support was available, or how frequently the nurses could visit Gregory, 2019). This can result in compromises with insulin regimens leading to poorer glycaemic control and greater risk of long-term complications .

The stigma of injecting insulin/checking blood glucose
This was a barrier to managing diabetes with insulin in Dysch et al.

Technology
Technology to facilitate or inhibit diabetes management in people with intellectual disabilities using insulin, emerged briefly in the results. For example, issues with glucometers not working properly featured in Cardol et al. (2012a) and the benefits of a talking glucometer were mentioned by Maine et al. (2017). There were practical challenges to using an insulin pen described by Hale et al. (2011). In their discussion section, Hale et al. (2011)

| Supported self-management
The concept of self-management in diabetes is promoted among people with diabetes (Diabetes UK, 2009). Being unable to self-manage can have negative connotations in terms of how the person perceives themselves, and how other people perceive them (Cardol et al., 2012a;Dysch et al., 2012). In reality, people with intellectual disabilities and diabetes are not the only ones in need of support, self-management is complex and every person with diabetes requires support to some extent (Diabetes UK, 2009

| Inequalities
There was evidence of inequalities. According to the Equality Act (2010), people with intellectual disabilities are entitled to reasonable adjustments to their care. Where there is a lack of reasonable adjustments to care, inflexible services, inadequate provision of diabetes education or negative attitudes from professionals Cardol et al., 2012a), people with intellectual disabilities have more difficulty achieving optimal diabetes management with insulin. These issues go beyond diabetes care. The COVID-19 pandemic has highlighted the stark inequalities facing people with intellectual disabilities. Williamson et al. (2021), revealed that people with intellectual disabilities have distinctly increased risks of hospital admission and death from COVID-19. Courtney and Cooper (2021) stress that more work must be done to reduce the health inequalities exposed and amplified by the pandemic.
Despite barriers, attempts to reduce inequalities for people with intellectual disabilities who use insulin were evident throughout the data. There were positive attitudes expressed by some healthcare professionals and support workers who wanted to empower people with intellectual disabilities and facilitate their autonomy Trip et al., 2016;Whitehead et al., 2016), and examples of reasonable adjustments such as extra appointment time and access to adapted resources. Gregory's (2019) service improvement project addressed some of the barriers for people who require support with their insulin, but such projects are not nationwide.

| Education and training
The need for appropriate diabetes education for people with intellectual disabilities was apparent from this review. Participants with intellectual disabilities expressed wanting more knowledge and information about their diabetes (Cardol et al., 2012b;Hale et al., 2011). This is consistent with the findings of Maine et al. (2017), and Holden and Lee's (2021) systematic review about the barriers and enablers to optimal diabetes care for adults with intellectual disabilities. Holden and Lee (2021) found that current structured group education courses are not appropriate to the learning needs of adults with intellectual disabilities. Adapted programmes, such as DESMOND-ID for people with type 2 diabetes and intellectual disabilities have been developed (Taggart et al., 2018), but such programmes are not available nationally (Maine et al., 2017). Accessible patient resources and information for people supporting those with intellectual disabilities are available (Diabetes UK, 2022), so it is important that people know how to access these.
Family, support staff and healthcare professionals require information, education, and training to be confident and competent to facilitate diabetes management with insulin for people with intellectual disabilities.
Practical skills such as being able to use a glucometer or insulin injection are important, but this review demonstrates that knowing how to facilitate self-management and be empowering towards people with disabilities are also essential to working in a person-centred way. This is consistent with Maine et al.'s (2020) review into the experience of type 2 diabetes self-management in adults with intellectual disabilities and their caregivers, which found overall inconsistency in staff knowledge and training. Maine et al. (2017) advocated caregiver training to support and enhance positive self-perceptions in people with intellectual disabilities.
The passing of an amendment to the Health and Care Bill in England means that training in understanding the needs of people with intellectual disabilities for all NHS health and social care staff will be compulsory (Walker, 2022). This is a positive step, but gaps remain in specific training for people supporting individuals with intellectual disabilities to manage their diabetes.

| Technology
Technology is increasingly important in diabetes management (Li & Hussain, 2020), yet there was little mention of this in the review data.
This is likely to be because diabetes technology has accelerated in recent years. Gregory (2019)

| LIMITATIONS OF THE DATA
The included publications were not research specifically focussing on diabetes management with insulin for people with intellectual disabilities, so a more in-depth study to address this is required. There was a lack of patient and public involvement in the research processes of the papers, which needs to be addressed if research is to be collaborative, empowering, and high quality (NIHR, n.d.). In the studies which included people with intellectual disabilities as participants (Cardol et al., 2012b;Dysch et al., 2012;Hale et al., 2011;Maine et al., 2017;Paterson et al., 2020;Rouse & Finlay, 2016;Whitehead et al., 2016).
The intellectual disability was described as 'mild' or 'moderate'there was almost no reference to people with intellectual disabilities who are unable to participate in conventional verbal interviews or discussion about why they were excluded from participating. The needs of people with disabilities who cannot express themselves through interview have been largely ignored in the diabetes research to date, so inclusive research is recommended. Studies which include participant observation could enable exploration into people's lived experiences and healthcare practices.

| Strengths and limitations of this review
This systemised review has offered insights into an issue that has previously been unexplored, and Patient and Public Involvement (PPI) was integral to the development of the research question. There was thorough analysis of each paper by both reviewers. However, there are limitations because the searches were limited to three databases and did not include grey literature, or papers not published in English.
The authors do not have an intellectual disability or diabetes, and it is recognised that their interpretations may be different to those of people who have personal experience of these. PPI throughout the research process is proposed for future research.

| CONCLUSION
Supported self-management is crucial to optimising diabetes management and people with intellectual disabilities are entitled to reasonable adjustments to care, but this systemised review into the barriers