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Efforts to cut the burden of morbidity and mortality associated with diabetes will take on increasing importance with prevalence spiralling ­ Dr Andrew Farmer advises GPs on practical strategies

Diabetes is a disease of startling statistics. Latest estimates suggest there are around 1.8 million people with diagnosed diabetes in the UK, and a further million undiagnosed cases. By 2010 the number of people with diabetes is projected to rise to three million as a result of the ageing population and the rapidly rising prevalence of obesity. Around 5 per cent of the NHS budget ­ £10 million a day ­ is currently spent on treating diabetes and its complications, with spending predicted to rise to consume 10 per cent of the NHS budget by 2011.

Type 2 diabetes is one of the main causes of premature mortality, with life expectancy reduced by up to 10 years on average. More than three-quarters of all deaths in type 2 diabetes patients are due to cardiovascular disease. Diabetes also leads to a wide range of disabling complications.

More optimistically, there is now a strong evidence base for the prevention, early detection and treatment of the range of life-threatening and disabling complications ­ and good primary care has a crucial role to play.

Complications strike early

In common with many chronic diseases, type 2 diabetes is characterised by an insidious course during which patients are unaware of progression of risk factors and onset of complications. Even at an early stage of the disease there are signs of future problems. Half of patients recruited to the UK Prospective Diabetes Study (UKPDS) already had one or more complication ­ such as retinopathy or an abnormal electrocardiogram ­ at diagnosis.

Complications, once present, are often not reversible so an emphasis on prevention is crucial. However, detection of the early signs of complications followed by appropriate treatment may prevent progression.

UK primary care has many features that facilitate care for people with diabetes and practiced-based registers can be used to organise regular recall and review. But the generalist skills of the primary care team need to be supplemented by training in, and regular use of, specialised skills. At their simplest these skills includes examination for neuropathy with a monofilament ­ at their most complex, primary care intervention may extend to initiating insulin therapy.

A routine annual review is the cornerstone of the effort to prevent complications in type 2 diabetes patients, and the quality and outcomes framework provides a foundation for that to take place. The annual review provides an opportunity for clinical assessment, review of risk factors and discussion about lifestyle changes and pharmacological therapy.

For many patients, an annual check will be sufficient, either because the disease is well controlled or because the majority of care is provided by a hospital. But some patients may need to be seen more often for more detailed assessment and monitoring or for active management of risk factors such as high blood pressure, a poor lipid profile or the failure to achieve glycaemic targets.

Setting realistic targets

It is important to bear in mind that the diabetes outcome indicators set out in the quality framework are not intended to act as targets for individual patients. For example, the more stringent of the two Q&O indicators for HbA1c is set at

7.4 per cent ­ but, in contrast, NICE recommends that patients should be set an HbA1c target between 6.5 and 7.5 per cent based on the risk of macrovascular and microvascular complications.

In some patients, hypoglycaemic episodes or lifestyle issues may require a target to be set above these levels, and for others a target as low as 6.5 per cent may be appropriate. The incremental system of allocating quality points and the system of exception reporting allows realistic targets to be set for the majority of patients.

Key complications

The table overleaf sets out the prevalence of key complications in type 2 diabetes patients together with appropriate screening and referral policies.

CHD and stroke

Coronary heart disease and stroke are the major cause of mortality and a significant cause of morbidity among people with diabetes. CHD risk is increased by two- to four-fold compared with people without diabetes. Increased risk is due to a combination of elevated risk factors such as blood pressure and widespread metabolic abnormalities including abnormalities of lipoproteins and blood vessel linings and increased clotting factors.

Action to meet blood pressure, glucose and lipid targets, along with steps to reduce smoking, remains the cornerstone of reducing cardiovascular risk.

Non-pharmacological approaches are important to address these risk factors, but failure to respond to measures such as exercise and dietary changes within three months or so should highlight the need for drug treatment in addition to a maintenance of lifestyle change.

Large-scale randomised trials have confirmed the effectiveness of blood pressure and cholesterol lowering in improving outcomes.

Oral glucose lowering therapy can be titrated to meet glycaemic targets. The UKPDS suggested a 1 per cent drop in HbA1c lowers CHD risk by about 15 to 18 per cent. An HbA1c target should be set at between 6.5 and 7.5 per cent, depending on the individual patient's level of risk factors.

Up to four different antihypertensive medications may be required to achieve blood pressure levels of less than 140/80. Home blood pressure monitoring may also be a means of assessing treatment, but clinic and daytime ambulatory blood pressures differ by an average of 12/7mmHg.

Treatment with a statin should aim to reduce total cholesterol to below 5mmol/l, or by

25 per cent ­ whichever is the lower ­ or to reduce LDL-C below 3mmol/l or by 30 per cent, whichever is lower.

Statins reduced CHD rates by 27 per cent and 36 per cent respectively in the recent Heart Protection Study and Collaborative

Atorvastatin Diabetes Study (CARDS), even among those with cholesterol levels within the normal range. Stroke rates were reduced by 25 and 47 per cent respectively.

Statins are likely to benefit a wide range of people with diabetes, although the benefits of treating all patients, particularly those with an overall 10-year CHD risk below 15 per cent, are not yet established.

Retinopathy

Background retinopathy is common but does not always progress. Proliferative diabetic retinopathy is a sign of progressive disease and untreated retinal ischaemia may lead to new blood vessels, haemorrhagic and retinal detachment.

Good glycaemic and blood pressure control can significantly reduce the risk. The incidence of proliferative retinopathy is halved by intensive glucose control.

Lesions can occur at the peripheries of the retina and wide papillary dilatation is mandatory during screening. Screening programmes are now in place for diabetic retinopathy in most districts. Laser photocoagulation of the peripheral retina is almost uniformly successful in preventing blindness.

Foot problems

Neuropathy is present in 40 per cent of patients within 10 years of diagnosis and the lifetime incidence of foot ulcers is around 15 per cent.

Neuropathy and peripheral vascular disease are both linked to hyperglycaemia and tight control reduces the risk of problems. The development of peripheral neuropathy was reduced by 69 per cent by tight glucose control in the Diabetes Control and Complications Trial (DCCT).

The feet should be inspected for ulcers at the annual review. Loss of light touch and vibration sensation are the early warning sign of neuropathy, with vibration and 10g monofilament perception significantly related to the risk of developing a foot ulcer. It is also important to check for the presence of ischaemia; if the dorsalis pedis or posterior tibial artery is not palpable, use a doppler to check.

If neuropathy or ulcers are detected, early referral to a podiatrist is important for regular monitoring and advice on how to prevent progression. Nail and skin care and pressure-relieving footwear can help avoid foot deformity (eg Charcot foot). In patients with ulcers a contact cast can improve healing.

Where peripheral vascular disease is present, intensive management of blood pressure, glycaemia and lipids is particularly important ­ high cholesterol and high blood glucose are both associated with an increased risk of amputation.

Renal disease

Within 10 years of diagnosis a quarter of people with type 2 diabetes have microalbuminuria. Progression to proteinuria and renal failure occurs at a similar rate, but the high mortality associated with these conditions means the number of people who survive with end-stage renal failure and type 2 diabetes is relatively low. A test for microalbuminuria should be done at diagnosis and at every annual review. A urinary albumin(mg)/creatinine(g) ratio greater than 0.3 indicates microalbuminuria. Intensive blood pressure control (BP<120 0)="" with="" the="" use="" of="" ace="" inhibitors="" reduces="">

Other complications

Depression

Depression is present in 18 per cent of men and 28 per cent of women with diabetes, about twice the rate in the general population. The extent to which this reflects the increased stresses of living with a progressive disease,

or changes in brain biochemistry, is not clear.

Low mood is associated with feeling unable to influence the course of the disease, so an active approach, involving patients in monitoring their condition and in decisions about treatment, may be helpful.

In the presence of significant mood disorder, referral and/or treatment with antidepressants or counselling should be considered.

Sexual dysfunction

Estimates of the prevalence of erectile dysfunction among diabetic men range from 35 to 75 per cent. Autonomic neuropathy and small and large blood vessel disease can contribute to the problem. Concern about health can also lead to impotence. Following a detailed assessment and examination, a phosphodiesterase type 5 inhibitor (PDEI) (such as sildenafil, tadalafil or vardenafil) taken before sexual activity helps a proportion of people, although use of nitrates is a contraindication.

If a PDEI is not effective, then referral to a specialist erectile dysfunction clinic may be an option if available. Use of a vacuum device or direct injections of alprostadil into the corpus cavernosum are helpful for some.

Conclusion

People with diabetes are a vulnerable group. Complications are common, but develop over a long period of time. Those complications are preventable with good care.

Primary care is well suited for the surveillance and routine care of people with type 2 diabetes. The quality and outcomes framework provides a set of targets that are consistent with ­ and will reward ­ good care.

Although most people will be seen annually within the practice, those who have blood pressures, lipids or blood glucose that could be further improved will need to be seen more frequently.

Systematic recording, clear protocols for progression of therapy and the involvement of patients in decisions about their management will all support improved disease control.

Andrew Farmer is a research lecturer in primary health care at the University of Oxford. He also works as a GP in Oxfordshire and is a research associate at the Oxford Diabetes Trials Unit, the centre that

co-ordinated the UK Prospective Diabetes Study

Key studies

1 UK Prospective Diabetes Study (UKPDS) Group:

·Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes (UKPDS 38). BMJ 317:703-713, 1998

·Development and progression of nephropathy in type 2 diabetes: (UKPDS 64). Kidney International 63:225-232, 2003

·Intensive blood glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with

type 2 diabetes (UKPDS 33).

Lancet 352:837-853, 1998

2 The Diabetes Control and Complications Trial Research Group: The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus.

N Engl J Med 329:977-986, 1993

3 Boyko EJ et al: A prospective study of

risk factors for diabetic foot ulcer.

The Seattle Diabetic Foot Study.

Diabetes Care 22:1036-1042, 1999

4 Collins R et al: MRC/BHF Heart Protection Study of cholesterol-lowering with simvastatin in 5963 people with diabetes: a randomised placebo-controlled trial.

Lancet 361:2005-2016, 2003

5 Selvin E et al: Meta-Analysis: Glycosylated Hemoglobin and Cardiovascular Disease in Diabetes Mellitus. Ann.Intern.Med. 141:421-431, 2004

6 Colhoun HM et al: Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 364:685-696, 2004

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