Type 1 diabetes is an autoimmune condition which tends to present acutely, with a swift and catastrophic loss of beta cell function in the pancreas leading to significant hyperglycaemia and, in some cases, potentially life threatening ketoacidosis (Diabetes UK, 2020). There is still a lack of clarity about why people develop type 1 diabetes, and as yet, prevention is not possible. In contrast, type 2 diabetes has a more gradual onset, with research showing that people often move through a process of normal insulin and glycaemic levels, to insulin resistance and hyperinsulinaemia, through to pre-diabetes and then to diabetes, with the potential to develop vascular complications (Stehouwer, 2018). At each stage there is the potential to halt, or at least slow down, the process and improve outcomes, often through lifestyle changes (Dunkley et al, 2014; Sun et al, 2017).
By the end of this article the reader should be able to:
- Understand how pre-diabetes and metabolic syndrome are defined
- Evaluate the impact of pre-diabetes as a cardiovascular risk factor
- Consider the interventions, pharmacological and non-pharmacological, that can improve cardiovascular risk in people with pre-diabetes
- Reflect on the way in which general practice nurses can support people with pre-diabetes to implement change.
Definition of pre-diabetes and metabolic syndrome
Worldwide, there are more than 400 million people with pre-diabetes, and it has been estimated that more than 470 million people will have prediabetes by 2030 (Middelbeek and Abrahamson, 2014). Pre-diabetes (or to use the more clinical term, non-diabetic hyperglycaemia) is a state of impaired glucose regulation where the body moves from a euglycaemic state (normal levels of blood glucose) to a position where increasing levels of insulin resistance result in higher and harmful sugar levels in the bloodstream (National Institute for Health and Care Excellence [NICE], 2017a). As its name suggests, it is a precursor of type 2 diabetes. The World Health Organization (WHO) has defined prediabetes as being evident in two separate tests: impaired fasting glucose (IFG) defined as fasting plasma glucose (FPG) of 6.1–6.9 mmol/l and impaired glucose tolerance (IGT) after a glucose tolerance test where the 2-hour plasma glucose is 7.8–11.0 mmol/l (WHO, 2006). The American Diabetes Association includes haemoglobin A1c (HbA1c) as a diagnostic tool, with a level of 5.7% to 6.4% (39–46 mmol/mol) indicating prediabetes, whereas NICE states that people at ‘high risk’ of diabetes will have an HbA1c between 42–47 mmol/mol (NICE, 2017a; American Diabetes Association, 2019). To be eligible for the NHS Diabetes Prevention Programme, people should have a HbA1c 42–47 mmol/mol (6.0–6.4%) or a fasting plasma glucose (FPG) of 5.5–6.9%. Family history can also be a risk factor. Certain populations, such as Asia, may present with a lower BMI but still be at risk of metabolic syndrome and pre-diabetes.
Insulin resistance is a result of abdominal obesity, and both of these conditions are linked to hypertension and dyslipidaemia, leading to the phenomenon often referred to as metabolic syndrome (Huang, 2009). Metabolic syndrome is defined as being present when an individual has three or more of the factors listed in Table 1 (International Diabetes Federation [IDF], 2006).
Table 1. Risk factors for metabolic syndrome
| Risk factor | Level associated with higher risk |
|---|---|
| Central obesity |
|
| Raised blood glucose level |
|
| Raised blood pressure |
|
| Triglycerides |
|
| Low HDL cholesterol |
|
If an individual has three or more of these risk factors they fit the profile for someone with metabolic syndrome, which is linked to an increased risk of developing diabetes and cardiovascular disease. People who have already been diagnosed with type 2 diabetes may also have metabolic syndrome.
The impact of pre-diabetes as a cardiovascular risk factor
The fact that the body has moved into a pre-diabetic state indicates that cardiovascular risk is also likely to be higher, mainly because of the links between hyperglycaemia and other known cardiovascular risk factors such as hypertension and dyslipidaemia (IDF, 2006). According to Grundy (2012), pre-diabetes impacts on both microvascular disease and macrovascular risk. This view was supported by a meta-analysis by Huang et al (2016), which identified that the health risk appeared to increase in people with a fasting blood glucose as low as 5.6 mmol/l or an HbA1c of 39 mmol/mol. Brannick and Dagogo-Jack (2018) describe the pathophysiology which drives cardiovascular risk in people with pre-diabetes as being based on insulin resistance, alpha- and beta-cell dysfunction, increased lipolysis, inflammation, and suboptimal incretin effect. The features associated with metabolic syndrome have also been shown to lead to endothelial and vascular smooth muscle dysfunction, leading to atherosclerosis (Papa et al, 2013).
Furthermore, while it is known that people with diabetes are at increased risk of heart failure, irrespective of their cardiovascular status (Macdonald et al, 2008), Kristensen et al (2016) also found that people with pre-diabetes were at higher risk of hospitalisation for heart failure and cardiovascular mortality compared with those with HbA1c below 42 mmol/mol.
Lifestyle interventions
In people with pre-diabetes, the aim should be to treat all the modifiable risk factors of metabolic syndrome through lifestyle interventions, especially by encouraging weight loss and increasing physical activity levels. Pharmacological interventions can be considered in addition to lifestyle changes in order to improve blood glucose levels, blood pressure and the lipid profile. As progression to type 2 diabetes will increase cardiovascular risk, metformin can be used to delay the onset of diabetes in those with pre-diabetes (NICE, 2017b).
In the Diabetes Prevention Program (DPP, 2002; Ratner et al, 2005; Lindström et al, 2003) lifestyle interventions, including dietary advice and increased physical activity levels, including circuit-type resistance training, were recommended. Weight loss was significantly higher in the active group (4.5 kg vs 1 kg). The active group had lower blood pressure levels post-intervention and demonstrated a reduced need for antihypertensive medications. With regard to lipid levels, the active group had increased HDL cholesterol, lower triglyceride levels and a reduction in LDL during approximately 3 years of follow-up, reducing the need for lipid-lowering medications. The Mediterranean diet has also been shown to have a positive impact on the cardiometabolic profile, with greater weight loss and improvement in inflammatory markers (markers for cardiovascular disease risk) compared with general lifestyle counselling (Esposito et al, 2015).
Public Health England recommends that to prevent obesity, most people need to do 45–60 minutes of moderate-intensity activity a day, particularly if they do not reduce their energy intake (NICE, 2014). People who have been obese and have lost weight need to consider doing 60–90 minutes of activity a day to avoid regaining weight (NICE, 2014). This is potentially off-putting for people who do little or no exercise and they could feel demotivated by this prospect. Fortunately, more recent and novel approaches have focused on high intensity interval training (HIIT) as a way of improving cardiovascular disease risk factors. Francois et al (2018) found that HIIT may be an effective means to reduce the burden of cardiovascular complications in type 2 diabetes, and Costa et al (2018) demonstrated a favourable impact of HIIT on hypertension. The key message here is that tailored interventions may help people to improve lifestyle behaviours, lose weight and reduce their risk of developing diabetes and cardiovascular disease.
Pharmacological interventions
There is some evidence for pharmacological interventions for reducing diabetes risk in people with impaired glucose regulation, including metformin (DPP, 2005; Salpeter et al, 2008) pioglitazone (DeFronzo et al, 2011), acarbose (Chiasson et al, 2002), and liraglutide (le Roux et al, 2017). There is also some evidence to say that liraglutide can help to reduce cardiovascular risk factors (Chiasson et al, 2003; Marso et al, 2016). In established type 2 diabetes, the sodium-glucose co-transporter 2 (SGLT2) inhibitors have also been shown to support weight loss and provide cardiovascular benefits (Buse et al, 2020).
Lipid-lowering therapies should generally only be used for primary prevention of cardiovascular disease in people with a cardiovascular disease risk score of 10% or more (or in familial hypercholesterolaemia) (NICE, 2016) and this is especially so in people with pre-diabetes, as statins have been associated with an increased risk of developing diabetes (Maki et al, 2018). As a result, using statins in people with low cardiovascular disease risk scores, especially those with prediabetes, could theoretically confer more harm than good. Conversely, ACE inhibitors, which NICE recommends should be the first-line treatment for people with diabetes and hypertension (NICE, 2019) are associated with slight reductions in blood glucose levels, as well as being cardioprotective and renoprotective, and may therefore offer extra benefits beyond blood pressure control (Herings et al, 1995).
Surgical interventions
Bariatric surgery (which includes gastric banding, balloons, sleeves and bypass) may not be the first option in reducing diabetes and cardiovascular risk in people with prediabetes, but in the Swedish Obese Subjects study, bariatric surgery was carried out in half of the participants, while the other half received usual care. After 15 years of follow-up, patients in all groups—diabetes, prediabetes, and normoglycemia—who underwent bariatric surgery had a reduced incidence of macrovascular complications, with the largest risk reduction seen in the prediabetes group (Carlsson et al, 2017).
Helping people to change
Working with people's own health beliefs about their lifestyle, their risk of developing diabetes and cardiovascualar disease will influence how engaged in behaviour change they might be, which might lead to improved outcomes (Tougas et al, 2015). Motivational interviewing is a consultation technique whereby people who needed to make a change to their lifestyle identify their own reasons for change, putting them in the driving seat and opening up a range of options for them to consider (Miller and Rose, 2009). Once the individual has decided that there is a need for change, two very simple questions provide additional information: how important is it for change to happen and how confident is the individual that this change can be achieved? The individual decides on a score of 0–10 for each question (Gold and Kokotailo, 2007). The confidence question is significant as people can be aware of how important a change is without having the confidence to make it, so differences between scores should be explored. High scores (>5) are indicative of an increased chance of success (Gold and Kokotailo, 2007). If the importance score is low, the reasons should be explored. The individual, supported by the clinician, can then consider what would help them to change and what might be a barrier. In someone with pre-diabetes, an open discussion may help to identify any false beliefs (‘it's in my family, there is nothing I can do about it’) and allow the clinician to take a non-judgemental approach to providing appropriate information and support, allowing new perceptions of health behaviours to be developed.
Doing things differently: group consultations for pre-diabetes
Running group consultations for people with pre-diabetes can increase patient satisfaction and interaction while at the same time optimising the use of time and resources. Although a search of PubMed for ‘group consultations’ or ‘shared consultations’ reveals no results, this has been shown from personal experience in the author's own practice, where weight losses were seen in the majority of patients attending group consultations, along with reductions in HbA1c. Two patients' HbA1cs remained the same (42 mmol/mol) and all of the others showed an improvement with over 50% now having an HbA1c which was lower than 42 mmol/mol (i.e., no longer pre-diabetic). All of the others were still pre-diabetic but with an improved HbA1c. Patients were very enthusiastic about how the group consultation setting specifically had inspired them to change by sharing ideas and experiences and supporting each other to change. This enthusiasm has been borne out by others who report that group consultations have had a positive impact on both the patient and clinician's experiences. The clinician can see many more patients in an hour than they normally might, while people with pre-diabetes get to discuss what they know and what they want to know with each other as well as with the clinician, plus, of course, clinics run to time. There is an opportunity to discuss different interventions as a group and to share resources, such as the PDFs of carbohydrate content that can be downloaded for free from carbsandcals. com. People attending the group consultations have also met up at the local ParkRun in order to take part, having previously lacked confidence to turn up alone. Overall, these consultations have demonstrated that they can have a positive impact beyond the clinical benefits, particularly with respect to the psychosocial elements of living with a long-term condition.
Conclusion
Diabetes is known to increase cardiovascular risk. However, there is an increasing body of evidence to say that pre-diabetes, or non-diabetic hyperglycaemia, carries its own cardiovascular risk, linked to the underlying pathophysiology and relationship to metabolic syndrome. The factors that drive this risk include lower levels of hyperglycaemia and blood pressure than those normally associated with type 2 diabetes and require careful consideration regarding appropriate pharmacological management in order to optimise the risk:benefit ratio. There is clear evidence that lifestyle interventions confer significant advantages in reducing the risk of progression from pre-diabetes to type 2 diabetes and that these changes can also improve cardiovascular risk. New approaches to weight loss and physical activity go beyond those traditionally recommended by national guidelines, but the most important aspect of any changes made is that they should be tailored to the individual.
Further information and resources:
- Diabetes.co.uk: Organisation for people living with diabetes
- Diabetes UK: National charity for people living with diabetes; professional section for healthcare professionals at diabetes.org.uk
- Group consultations FAQs: https://www.groupconsultations.com/wp-content/uploads/2018/10/primary-care-group-consultations-faq-1018.pdf
- Group consultation skills training: https://elcworks.co.uk/our-programmes/elc-group-consultations/
- Independent Diabetes Trust—free leaflets and resources: https://www.iddt.org/
- Primary Care Cardiovascular Society—free to join with free resources and national conferences: pccs-uk.org
KEY POINTS:
- Pre-diabetes, or non-diabetic hyperglycaemia, is associated with increased cardiovascular risk
- Feature of metabolic syndrome drive this risk
- Lifestyle changes and pharmacological interventions can help to reduce the risk of progression from pre-diabetes to type 2 diabetes and can also reduce cardiovascular risk.
- Newer approaches to weight loss and physical activity should be considered when supporting people to change
CPD reflective practice:
- What are the main topics you would cover in a consultation with someone with pre-diabetes?
- How could you use motivational interviewing to engage with people with pre-diabetes?
- How do you think group consultations would work in your practice? Would there be any particular benefits for your practice population?