• Early detection of complications requires a systematic surveillance programme involving regular review, examination and blood monitoring
• Complications particularly amenable to early detection include retinopathy, microalbuminuria and foot ulceration risk
• Surveillance also provides opportunities for review of control of the key cardiovascular risk factors: glycaemia, blood pressure and lipids
• Regular contact facilitates discussion on factors affecting quality of life including mood, hypoglycaemia, erectile dysfunction and driving safety monitoring of renal function often need to be carried out more frequently, outside the annual reviews.
Box 11.1 Minimum surveillance measures for diabetes
• Weight and body mass index
• Blood pressure measurement
• Serum cholesterol estimation
• Glycosylated haemoglobin (HbAlc)
• Estimated glomerular filtration rate (e-GFR)
• Foot examination
• Digital retinal photography
• Urinalysis for microalbumin
• Depression screening
Once the diagnosis of diabetes is confirmed, the patient should be entered into a structured programme of surveillance and follow-up. The purpose of surveillance is twofold: to identify the development of complications as early as possible and to address factors the treatment of which will prevent or delay their onset. The importance of this programme must be clearly explained as part of the initial patient education, emphasising its benefits and strong evidence base.
This chapter describes the techniques used to conduct diabetes surveillance (Box 11.1). Treatments and targets are discussed elsewhere in the book. Most of the surveillance measures required should be conducted at least annually. As discussed in Chapter 18, a regular habit of annual review is important both to improve concordance and to ensure that the process is completed. If some of the measures are taken opportunistically outside the annual review appointments then this may reduce the effectiveness of the programme, as the patient may be less inclined to attend for the remaining checks. However, blood pressure, glycaemic control and
Weight is a good index of the success of life-style change. Ninety percent of patients with type 2 diabetes are overweight or obese at diagnosis and benefit from weight reduction, particularly when this is associated with increased physical activity. Abdominal obesity carries a particularly raised risk of cardiovascular disease, so waist measurement is also useful to monitor success in reducing this risk factor. The patient should usually be weighed with coat and shoes off but otherwise clothed, on regularly calibrated scales, and preferably the same scales each time (Figure 11.1).
Blood pressure should be taken with the patient sitting down and after a few minutes rest, with the cuff at the same level as the heart and the elbow very slightly flexed. An appropriate sized cuff is important, as too small a cuff will give falsely raised readings. Initially it is worth checking the blood pressure in both arms, and if there is consistent difference then the arm with the highest pressure should be used in future for monitoring. It is also useful to measure the sitting and standing blood pressure, and this should be done annually particularly in elderly patients. A fall of greater than 20 mmHg after standing may be a sign of autonomic neuropathy (see page 73). If such a fall is associated
with postural hypotension symptoms this will affect blood pressure management and may be a contraindication to drug therapy. Alternatively, it may be associated with one of the drugs currently used to reduce blood pressure in which case it may resolve when this drug is stopped or changed to an alternative. Beta blockers, thiazide diuretics and alpha blockers are particularly likely to cause postural hypotension.
Patients should ideally have a fasting lipid profile measured annually, to include total serum cholesterol, HDL, LDL and fasting triglycerides. The majority of patients should be prescribed a lipid-lowering agent (see Chapter 5) irrespective of their baseline serum cholesterol. It will therefore usually be advisable to check the liver function tests on at least an annual basis.
Glycosylated haemoglobin (HbAlc)
The HbA1c is a reflection of average blood glucose values over the previous 2-3 months. In the past the value has been given as a percentage, which is not equivalent to a glucose value (frequently causing confusion). This is the percentage of haemoglobin A that has become glycosylated by exposure to plasma glucose during the lifespan of the red blood cells. The new IFCC units for HbA1c reporting discussed in Chapter 1 should resolve this confusion. Measurement should be made every 6 months, or at the very least annually. There is little point in repeating the measurement earlier than 2 months following a change in therapy, as it takes this long to change in response to red blood cell turnover. Other means of gauging control (including self-monitored blood glucose levels and symptoms of hypoglycaemia), may be used in the meantime to guide decisions on treatment.
Estimated glomerular filtration rate (e-GFR)
Whilst at best an approximation, this marker is a much more adequate index of renal function than serum creatinine, as it takes account of age, sex and ethnicity. In the UK, the e-GFR can be requestedonablood sample at thesametimeasthe urea, electrolytes and creatinine, and is calculated automatically by the laboratory using the MDRD formula (although the adjustment for ethnicity is not included). The e-GFR should be measured at least annually, and more frequently in patients whose renal function is reduced or at risk of declining, in those taking medication that can affect renal function such as diuretics, non-steroidal anti-inflammatory drugs, or ACE inhibitors, and those taking drugs that are contraindicated if renal function is poor (such as metformin). Abnormal renal function may influence the choice of statin (see page 55). Such decisions are much more securely based on e-GFR than on serum creatinine measurements.
More than one e-GFR measurement is required to confirm renal impairment, and unexpectedly low values should be followed up by repeated measurements to confirm (as well as to exclude progressive decline), as levels may be artificially reduced in the short term by dehydration, recent changes in medication, or other factors. To maximise the validity of an e-GFR measurement, the patient should avoid ingesting meat for 12 hours before the blood sampling.
All patients with diabetes should have a thorough foot examination atleast annually, and in those with signs of complications or 'at-risk' features this frequency shouldbe increased. The examination should include, as a minimum, the following:
• Inspection of the general health of the feet: signs of deformity, hair loss, loss of skin integrity, loss of sweating, swelling of joints, callosities, nail health, fungal infection between the toes. Deformity or swelling may suggest an underlying Charcot's neuroarthropathy (see Chapter 14). Callosities suggest abnormal distribution of weight over the sole, which may indicate peripheral neuropathy.
• Assessment of vascular sufficiency: temperature of the skin, detection of dorsalis pedis and posterior tibial pulses, capillary return at the toes. A Doppler device (Figure 11.3) may assist in assessing vascular sufficiency, particularly when used in experienced hands to measure ankle brachial pressure index, but if the pedal pulses cannot be detected manually then the arterial supply should be considered abnormal.
• Assessment of neurological integrity: light touch sensation using a 10 g nylon microfibre device at all of the 'at-risk' areas (see Figure 14.6) and vibration sense at the great toe and ankle; Achilles tendon reflex (Figure 11.4).
Advice and treatment of foot complications is covered on pages 64-71.
Traditional fundoscopic examination, even in experienced hands and following dilatation of the pupils, is not an adequate means of excluding early retinopathy. The gold standard technique is digital retinal photography of both eyes following dilatation, and examination of the images by an experienced professional who analyses such images regularly (Figure 11.5). Dilatation should be achieved using a short-acting topical mydriatic such as tropicamide 0.5%. Retinopathy is present at the time of diagnosis in 37% of type 2 patients, and newly diagnosed individuals should not be left to wait 12 months before the annual screen is organised.
Dipstix are available for the detection of microalbumin, but for accurate quantification a laboratory will measure the albumin: creatinine ratio. This is abnormal if >2.5 for men and >3.5 for women. A positive finding should be followed up with a second sample as spurious positive results may occur, particularly if infection is present. If unconfirmed on a second sample then a third
should be arranged, and two out of three positive is considered conclusive. Angiotensin converting enzyme inhibitors (ACEI) and tight control of blood pressure in patients with urinary microalbumin are extremely beneficial (see Chapter 12).
As with many long-term health problems, patients with diabetes are at significantly higher risk of depression, and symptoms may not be reported. Active questioning to screen for depressive symptoms should be part of an annual diabetes review. In the UK, this involves the use of two validated screening questions. Positive indications of an underlying depression should be followed by a formal assessment using a validated instrument such as the PHQ-9 (see Chapter 16).
Other issues that need to be addressed on a regular basis include:
• Erectile dysfunction: Unless clearly inappropriate a question about erectile dysfunction should be included in an annual review to male patients. This problem is common and treatable, but may go unreported because of embarrassment. If medication is required (e.g. Sildenafil) this should be placed in the 'Repeats' screen along with other medication unless there is a reason not to.
• Driving safety: In the UK, patients treated with oral medication should be advised to inform the Driving and Vehicle Licensing Authority (DVLA), even though currently this is not legally required unless they have a complication likely to impair driving ability (e.g. visual or affecting limb function). Provided they satisfy this criterion they will be able to retain their 'til 70' licence but given information about when and how to inform DVLA of changes in circumstances. If they do not inform the DVLA they will not have actually broken the law, but if in future they then do develop problems affecting driving ability they may not realise that they then are obliged to report them. They are on stronger grounds regarding insurance if they have informed the DVLA and received this advice. Patients on insulin should all be advised that they are legally obliged to inform the DVLA and this advice should be written in the notes. They are likely to be allowed to continue driving provided they have adequate glycaemic control, are free of disabling hypoglycaemia, have hypoglycaemia awareness, and no complications that affect driving ability. The DVLA guidelines are updated every 6 months so if in doubt it is worth accessing their website (given below). • A holistic perspective: It is easy to become fixated on 'box-ticking' when conducting surveillance reviews. Box-ticking is, in fact, extremely important if an assessment is to be comprehensive, and screen templates may facilitate this process. But an assessment should also include some protected time for the 'free-text' issues that are important for quality of life. This is, after all, one of the major goals of diabetes management. These aspects are not as easily quantified or measured but are valued by patients. Relationship issues, educational progress, family support, work stress and other anxieties, and future life plans may all come to light to a receptive ear in a supportive environment. Spending time on these will build the clinician-patient relationship and reap benefits in future when difficult management decisions need to be shared.
Surveillance for complications is a major component of diabetes care, and should take the form of regular reviews (at least annually) with protected time for a comprehensive assessment of the patient's needs. It cannot be managed by a single health care professional, but requires a teamwork approach using a shared care protocol, adapted to locally available resources and understood by all involved. This protocol should, where possible, be discussed with the patient to facilitate the early detection and treatment of complications. Routine surveillance should also include an exploration of the psycho-social issues that affect quality of life but that may not otherwise be reported.
Driving and Vehicle Licensing Authority. 'At a Glance' Guide to Medical
Standards of Fitness to Drive. www.dvla.gov.uk/medical/ataglance.aspx National Institute for Health and Clinical Excellence. Clinical Guideline 66. Diabetes - type 2 (update). May 2008.
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