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Glycaemic control in type 2 diabetes

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VOL: 98, ISSUE: 19, PAGE NO: 56

Jill Rodgers, RGN, MSc, BA, and Rosemary Walker, RGN, BSc, FETC, are partners, In Balance Healthcare UK

Type 2 diabetes has historically been considered less serious than type 1 and has been described in terms such as 'mild diabetes', 'borderline diabetes' or 'a touch of diabetes'. These terms are redundant because there is ample evidence to indicate that type 2 diabetes is equally, if not more, complex than type 1 (King's Fund, 1996). Therefore, attention must be paid to all aspects of the disease. The National Institute of Clinical Excellence (NICE) has recently finished the final consultation period on their guidelines (NICE, 2002), and these guidelines, as they currently stand, form the basis of the recommendations in this article. The final guidance is expected in July.

Type 2 diabetes has historically been considered less serious than type 1 and has been described in terms such as 'mild diabetes', 'borderline diabetes' or 'a touch of diabetes'. These terms are redundant because there is ample evidence to indicate that type 2 diabetes is equally, if not more, complex than type 1 (King's Fund, 1996). Therefore, attention must be paid to all aspects of the disease. The National Institute of Clinical Excellence (NICE) has recently finished the final consultation period on their guidelines (NICE, 2002), and these guidelines, as they currently stand, form the basis of the recommendations in this article. The final guidance is expected in July.

Why is glycaemic control important in type 2 diabetes?
When assessing glycaemic control, patient self-monitoring results are often used, but changes to prescribed medication are often made on HbA1c levels which provide an overview of glycaemic control over a period of up to three months before the test. HbA1c is estimated from venous blood samples taken at three- to 12-month intervals, although some near-patient testing equipment can use capillary blood samples. HbA1c levels in the non-diabetic population are around 4.5-6.5%, and higher levels are often seen in the diabetic population.

Type 2 diabetes usually occurs later in life in people who are overweight and have co-existing hypertension, hyperlipidaemia and/or coronary heart disease (CHD). However, this is changing. The prevalence of type 2 diabetes is rising among those of normal weight and even young people.

It is estimated that by 2010 there will be almost three million people diagnosed with diabetes (Diabetes UK, 2002), the majority of whom will have type 2. Until recent years, type 1 diabetes tended to steal the limelight - it attracts sympathy because it often occurs in childhood, the only treatment is insulin injections for life and it carries with it serious and potentially life-threatening complications. The Diabetes Control and Complications Trial (DCCT Research Group, 1993), a 10-year study, was terminated after nine years due to its conclusive results, showing without doubt that tight glycaemic control in type 1 diabetes reduced the level of these complications.

In type 2 diabetes, there was greater debate: tight glycaemic control can be difficult to achieve, and for many people can only be achieved by either multiple oral therapy or insulin injections, both of which may cause weight gain, which may then increase the risk of coronary heart disease. Health professionals face trying to strike a balance between reasonable glycaemic control without inducing excessive weight gain. However, in 1998, the UK Prospective Diabetes Study was published, which showed that tight glycaemic control in type 2 diabetes reduced microvascular complications without increasing the risk of CHD, despite weight gain with some therapies. The average HbA1c levels achieved in the study group were 7%, whereas in the control group the HbA1c levels averaged 7.9%.

The UKPDS recommendations stated that any reduction in HbA1c was likely to produce a benefit in reducing complications and that tight glycaemic control was worth striving for.

The proposed National Institute of Clinical Excellence (NICE) guidelines recommend that HbA1c targets of between 6.5-7.5% should be set for each individual, depending on their health status and known risk factors - the greater the risk, the tighter the control. HbA1c tests should also be carried out six-monthly in those whose condition is stable, and as frequently as two-monthly in those requiring medication adjustment or those with poor glycaemic control. While self-monitoring of blood glucose can help, it is recommended that this is only taught if there is a clear, recognised need and purpose and the patient agrees.

Use of oral therapy and insulin
Adding oral therapy and/or insulin is recommended for all people who experience inadequate glycaemic control. The NICE guidelines acknowledge that not all people take their medication regularly, and monitoring this should be part of routine care. If it is believed that medication is being taken, additional therapies should be added when necessary to reach the individual's HbA1c target.

The range of oral therapies has increased in recent years, as have the potential combinations of these therapies. The NICE guidelines have attempted to clarify which therapies should be used in different circumstances, as listed below.

Metformin is recommended as the first line drug of choice in those who are overweight, unless they have renal impairment, classified as a serum creatinine of greater than 130mmol/l. Where necessary, the addition of insulin secretagogues (sulphonylureas such as gliclazide, or the newer drugs repaglinide or nateglinide) should be the next step. Insulin secretagogues should only be used as first-line therapy in people of normal weight, or may be used alone in those who cannot tolerate metformin.

Thiazolidinediones (rosiglitazone or pioglitazone) are recommended only for those who cannot take both metformin and an insulin secretagogue, as previously recommended (NICE, 2000b). Alpha-glucosidase inhibitors (acarbose) are also mentioned as an alternative therapy that can be used if other oral drugs are not tolerated.

In all cases, if optimal oral therapy does not produce the desired glycaemic control, insulin should be considered the next step. When insulin is initiated, it is recommended that metformin is continued if tolerated, and where metformin is not tolerated, sulphonylureas should be continued.

Orlistat, a recently licensed weight-reducing drug, is seen as being useful in treating people with diabetes. NICE advises that it should be used in people with diabetes who have a body mass index of over 28 and have recently achieved a weight loss of at least 2.5kg (NICE, 2000b).

Lifestyle interventions
The guidelines acknowledge that there is limited evidence for the effectiveness of lifestyle interventions in type 2 diabetes. However, it is also recognised that dietary modification, increasing activity and losing weight all contribute to reducing risk factors such as hyperlipidaemia and hypertension.

Dietary recommendations are that the proportion of energy intake from different types of food should be 55-60% carbohydrate, 15-20% protein and 20-30% fat.

Following these recommendations has been shown to lead to improvement in both glycaemic control and lipid levels. Other evidence contained in the guidelines indicates that any intensified dietary intervention will improve glycaemic control, although the studies reviewed showed that people with type 2 diabetes did not necessarily achieve their weight loss targets. When interventions specifically aimed at weight loss were used, weight did reduce in the short term, but this did not necessarily improve glycaemic control.

The evidence for exercise is stronger, with most trials achieving both weight loss and improved HbA1c levels. However, in many cases this weight loss was not maintained for longer than six to 12 months.

Given the above evidence, it is difficult to decide how nurses can most effectively educate people with type 2 diabetes about lifestyles. Many people with diabetes say they are made to feel guilty about their lifestyles and feel they are to blame if they have poor glycaemic control. It appears that encouraging a balanced diet and increasing physical activity can improve glycaemic control to a limited extent, but the disease process itself is largely responsible for the progression of type 2 diabetes and the need for increased medication over the years, as shown by the UKPDS study (UKPDS Group, 1998).

Patient education
Evidence used to underpin the NICE guidelines indicates that most educational interventions have a small to moderate effect, although there is a lack of detailed descriptions of the types of interventions used. This makes it difficult to determine which elements of the studies are the most important to incorporate into practice. However, there is evidence in general diabetes literature about approaches that are more likely to facilitate behaviour change.

Sadly, diabetes education has often been delivered in an 'acute' care model, where the health professional makes decisions, gives advice and is generally in control of the treatment (Anderson and Rubin, 1996). There is ample evidence that this approach is likely to produce only short-term behavioural change - for a longer-lasting effect it needs to be recognised that people with diabetes are in control of their lives from day to day and make their own choices about their lifestyles.

An alteration of consultation styles to incorporate a more person-centred approach is more likely to result in behavioural changes than using persuasion or coercion (Anderson and Funnell, 2000).

There is also evidence that if health professionals support patients' autonomy they will be more motivated to self-care, which will ultimately result in improved HbA1c levels (Williams et al, 1998).

What is the role of nurses in improving glycaemic control in type 2 diabetes?
There is increasing recognition of the central role that nurses play in delivering diabetes care because of their unique position and skills. Diabetes is a chronic disease, and individuals benefit from continuity of care, understanding and time spent with them at significant points in their journey through diabetes.

Organisational skills are also required, to ensure that the care systems people with diabetes access are meeting both their medical and individual needs. It has been shown that 34% of diabetes clinics in primary care (where most people with type 2 diabetes receive care) are run by practice nurses alone (Pearce et al, 2000; Audit Commission, 2000).

Given the ubiquity and the increase in numbers of people with diabetes, nurses in all care settings will have contact with, and therefore the opportunity to influence, diabetes management. They are ideally placed to inform and educate those with diabetes, especially type 2, of the need for tight glycaemic control and provide support for them to achieve it. Examples of how this can be done include the provision of information, perhaps from organisations such as Diabetes UK, ensuring every person with diabetes has access to regular structured care and annual medical review, and updating educational skills and person-centred approaches to chronic disease management.

Nurses are also well placed to work with other professionals to optimise diabetes control, even when diabetes is not the main reason for contact. It is important to remember that the glycaemic control of type 2 diabetes has an impact on all concurrent conditions, such as wound-healing, infections, blood pressure, lipid levels and leg and foot ulcers. Nurses can positively influence these outcomes by paying close attention to diabetes control in all situations and highlighting its importance to other colleagues.

Practice nurses or diabetes specialist nurses can dramatically improve the knowledge and skills of their patients through education programmes and close teamwork with colleagues such as doctors, podiatrists, pharmacists and dietitians. In addition, such nurses are often the main link between the patient and other professionals. They can also network to 'troubleshoot' problems by, for example, direct dial 'hotlines' to specialist clinics or regular visits to primary care settings.

It is likely that the National Service Framework Delivery Strategy, expected this summer, will result in more opportunities for nurses to specialise in diabetes care.

Conclusion
The NICE guidelines contain very few surprises, but also may not reflect current practice for many health professionals. It is important to remember that the guidelines are at consultation stage only but are in line with current evidence and are unlikely to vary significantly when published in their final format.

Sadly, there is little guidance in the areas where nurses often have the greatest input and impact, namely education and lifestyle intervention.

With the publication of the NSF standards in December (Department of Health, 2001), and with the promise of a delivery strategy to be published this summer, the spotlight is on diabetes. We need to ensure that our efforts are geared towards those areas of care where we can make a difference - working towards tighter glycaemic control targets, ensuring medication is optimised, and using the best educational methods to make life better and reduce complication rates for people with diabetes.

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