Dr Sally Marshall explains how practical recommendations from NICE on prevention and early management of renal disease in type 2 diabetes should reduce morbidity

The recently published National Service Framework for Diabetes states that approximately 1.3 million people in England are known to have diabetes.1 A similar number are undiagnosed and the incidence is predicted to double in the next 10 years. About 85% have type 2 diabetes.

Although there are no robust recent figures for the UK, diabetes is the single most common cause of entry to renal replacement therapy worldwide.

The number of patients with diabetes beginning renal replacement therapy in the UK is rising, but still lags behind the rest of Europe. The majority have type 2 not type 1 diabetes and end-stage renal disease (ESRD) is more common in the ethnic minorities. Renal replacement therapy is costly for the country and miserable for the affected individual.

Over the past decade, evidence has accrued on the significance of microalbuminuria and proteinuria in predicting the later development of macrovascular disease2 and ESRD3 in type 2 diabetes.

Much research has also been published on therapy to delay and/or prevent the development of ESRD and on managing cardiovascular risk factors.

Despite this burgeoning knowledge, recent audit data have shown that many centres do not screen for microalbuminuria4 and the majority of patients with diabetes reaching ESRD receive inadequate therapy for blood glucose, lipid and blood pressure management.5

A systematic review of all this new evidence, linked to practical recommendations on preventing and managing early renal disease in type 2 diabetes, is therefore timely.

The National Institute for Clinical Excellence (NICE) guideline on prevention and early management of renal disease in type 2 diabetes is one of a series of five evidence-based guidelines for the management of type 2 diabetes.

Origin of the guideline

The series was originally commissioned through a collaborative programme between the Royal College of General Practitioners, the Royal College of Physicians, Diabetes UK (formerly the British Diabetic Association) and the Royal College of Nursing, and was later 'inherited' by NICE.

Details of the ethos driving the work, the methods used and governance issues surrounding the development of the guidelines have been described previously.6

The working group principally responsible for this guideline included diabetologists with a special interest in nephropathy, GPs, nurses and researchers skilled in performing systematic, evidence-based reviews.

Scope of the guideline

It is hoped that anyone involved with diabetes care will find the guideline useful, although the main target audience is people involved with the day-to-day care of diabetes patients. Thus the guidelines are limited to the prevention of renal disease and detection and management of early stagesoof disease, along with management of the associated increase in cardiovascular risk (see Figure 1, below).

Issues concerning advanced disease and renal replacement therapy are not reviewed.

Figure 1: Algorithm for the prevention and management of renal disease in type 2 diabetes*
*Reproduced from Management of Type 2 diabetes, renal disease - prevention and early management. NICE Inherited Clinical Guideline F, by kind permission of the National Institute for Clinical Excellence

Evidence base

The search and review strategies employed by the development team are comprehensive, robust and open. The grading of the evidence statements and recommendations allows readers easily to appreciate where evidence is strong and where recommendations are based on consensus opinion.

The guideline emphasises the overwhelming evidence of the significance of microalbuminuria and proteinuria in type 2 diabetes, as markers for cardiovascular risk and ESRD.

The risk of premature cardiovascular death is increased two- to three-fold in microalbuminuria and nine-fold in proteinuria. Although the risk of ESRD is lower for the individual patient, we must not lose sight of the fact that, because type 2 diabetes is so common, ESRD in type 2 diabetes is also common.

Clear guidance is also given on an annual screening programme. The plethora of urine samples and tests described in the literature has previously given rise to much confusion on the best way to identify those at higher cardiovascular and renal risk.

Much research has been based on the use of timed urine samples, either overnight or over 24h, which are obviously difficult to organise for large numbers of patients at regular intervals.

The guideline found sufficient evidence to recommend screening, preferably using early morning urine samples and an assay specific for albumin. Clear definitions of micro-albuminuria, using the albumin: creatinine ratio or urine albumin concentration are quoted, based on the increased cardiovascular and renal risk (see Figure 2, below).

Figure 2: Definitions used in the NICE guideline on prevention and early management of renal disease in type 2 diabetes*
*Reproduced from Management of Type 2 diabetes, renal disease - prevention and early management. NICE Inherited Clinical Guideline F, by kind permission of the National Institute for Clinical Excellence

The benefits of tight blood glucose and blood pressure control in preventing microalbuminuria are summarised, and clear targets for HbA1c (<6.5-7.5%) and blood pressure (<140/80mmHg) given (see Figure 3, below). Detailed advice on how to achieve good control is not provided, but is the subject of other guidelines in the same series.

Figure 3: Extract form the NICE guideline on prevention and early management of renal disease in type 2 diabetes*
*Reproduced from Management of Type 2 diabetes, renal disease - prevention and early management. NICE Inherited Clinical Guideline F, by kind permission of the National Institute for Clinical Excellence

A section details the care of those with urine albumin excretion in the higher risk range (see Figure 3, above). The need to exclude non- diabetic renal disease is discussed, and a plan of investigation suggested, based on consensus agreement in the absence of strong evidence on how to do so.

Great emphasis is placed on aggressive management of cardiovascular risk factors, although again detailed guidance is not given: this is provided in other guidelines in the series.

The evidence supporting the first-line use of angiotensin-converting enzyme (ACE) inhibitors for cardiovascular and renal protection is reviewed. Unfortunately the guideline went to press before the recent trials of angiotensin II receptor blocking agents were published, but their results confirm the view taken in the guideline that blockade of the renin-angiotensin system affords renal and cardiovascular benefit in type 2 diabetes.

The need for extremely good blood pressure control (<135/75mmHg) is emphasised, as is the likelihood of combination antihypertensive therapy being needed to meet such strict targets. The review found very little data to guide selection of drug combinations, so this is left to practitioner choice.

The NICE publication also includes a booklet for people with diabetes and their carers which summarises the important messages contained in the guideline.

Improving patient care

There is good evidence that many diabetes clinics in the UK currently do not offer screening for early diabetic kidney disease. This guideline emphasises the need for such a programme, which is probably most efficiently done as part of the annual review, and provides clear details of a simple screening system. This should not significantly increase the workload of healthcare professionals or inconvenience people with diabetes.

For those categorised as being at higher risk of renal or cardiovascular disease, appropriate targets are set for tight glucose and blood pressure control and aggressive management of other cardiovascular risk factors.

When read alongside the other guidelines in this series, this guideline should give healthcare professionals and people with diabetes a clear idea of what constitutes good diabetes care and how to achieve it.

Promoting best practice

This guideline deals with an area of diabetes care in which there has been an explosion of knowledge recently. UK audit data show that this knowledge has not been translated into clinical practice and that many patients receive suboptimal care.

The guideline recommends and presents the evidence base for an annual screening strategy for early diabetic renal disease and provides detailed information on the best management of those with early diabetic nephropathy.

Implementation of these recommendations will undoubtedly reduce the number of people with type 2 diabetes who develop nephropathy and slow the progression to ESRD in those who do develop micro- albuminuria. Cardiovascular benefit will also accrue.

The benefits to the individual are obvious, and potential financial savings to the NHS in preventing or delaying the need for renal replacement therapy are enormous.

References

  1. National Service Framework for Diabetes: Standards. Department of Health, UK, 2001.
  2. Dinneen SF, Gerstein HC. The association of microalbuminuria and mortality in non-insulin-dependent diabetes mellitus. A systematic overview of the literature. Arch Intern Med 1997; 157: 1413-18.
  3. Mogensen CE. Microalbuminuria predicts clinical proteinuria and early mortality in maturity-onset diabetes. N Engl J Med 1984; 310: 356-60.
  4. Audit Commission. Testing Times. A review of diabetes services in England and Wales. (National Report). London: Audit Commission, 2000.
  5. Dunn EJ, Burton CJ, Feest TG. The care of patients with diabetic nephropathy: audit, feedback and improvements. Q J Med 1999; 92: 443-9.
  6. Gadsby R. National guideline on diabetic footcare aims to reduce amputations. Guidelines in Practice 2000; 3: 27-36.

Copies of Management of Type 2 Diabetes. Renal disease - prevention and early management can be obtained free of charge from the NICE website (www.nice.org.uk) and from the NHS Response Line by telephoning 0870 1555 455 and quoting ref. N0061. A patient version of this document Screening for and early management of kidney (renal) problems can also be obtained by quoting ref. N0062 for an English version and N0063 for an English/Welsh version.

 

 

 

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