One needs to give consideration to glycaemic control, smoking, BMI, blood pressure and drug therapy, although not necessarily in that order. The evidence that improving blood glucose control and reducing weight would have a major impact on coronary heart disease risk in this case is weak. In contrast, blood pressure control is crucial; however, one needs to know that the reading taken on this visit is representative and not anxiety induced (so-called ‘white coat hypertension’). An electrocardiogram (ECG) may be helpful because evidence of left ventricular hypertrophy would imply long-standing hypertension; however, if this were normal, then repeated blood pressure checks should be arranged. A
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minimum of three recordings over a 3-month period would be appropriate, with consideration of drug therapy if the level remains above 140/80 mmHg. Aspirin is not currently recommended at this stage.
CASE 1.11 – A 76-year-old woman with type 2 diabetes and a stable blood pressure of 166/70 mmHg.
A1: Are further assessments required before the italicized finding provokes a drug intervention?
This patient with diabetes, ischaemic heart disease and peripheral vascular disease has isolated systolic hypertension confirmed by multiple assessments over time. The literature strongly supports reduction of her systolic pressure using drugs to a target of less than 130 mmHg. Further attention to weight, exercise and glycaemic control would be beneficial, but these will have minimal impact on her blood pressure. Apart from baseline urea and electrolytes (U&Es), no further investigations are required at this point.
A2: If drug therapy were indicated, which would be the most appropriate choice of agent?
The first-line antihypertensive agent in a person with diabetes and proteinuria should be an inhibitor of the renin–angiotensin system. This would typically be an ACE inhibitor, with consideration of an angiotensin II receptor blocker if side effects (most often cough) are experienced. In either case, check that U&Es have been performed before initiation and 7–10 days thereafter. For a substantial proportion of people with diabetes, monotherapy is not sufficient to achieve blood pressure targets, and additional classes of blood pressure medication will be needed. A typical second-line agent in this case would be a calcium channel blocker or a low-dose diuretic.
A3: What sort of follow-up is indicated?
The effect of drug therapy may take 2 months to become apparent. An interim target blood pressure of 160 mmHg is appropriate; if the patient feels well having achieved this, further increases in medication should be made, aiming for systolic blood pressure below 130 mmHg. Once stabilized, blood pressure can be checked every 3–6 months. Patients on ACE inhibitors and angiotensin II receptor blocker should have renal function and electrolytes checked at regular intervals (every 6 months) because renal function can deteriorate at any time. Additional tests are required if the dose of ACE inhibitor or angiotensin II receptor blocker is increased, additional medication is added, or there is intercurrent illness.
A4: What other issues need to be addressed with regard to cardiovascular risk?
Attention to glycaemic control, weight and exercise is justified but unlikely to have a significant impact on the risk of coronary heart disease. The patient’s other medications should be reviewed: the simvastatin dose should be increased to 40 mg once a day (the dose on which most of the evidence for this agent is based), and the dose of aspirin should be increased to 150 mg once a day, given her known ischaemic heart disease (i.e. secondary prevention).
CASE 1.12 – A 21-year-old woman with type 1 diabetes and
microalbuminuria (urinary albumin/creatinine ratio 3.7).
A1: Are further assessments required before the italicized finding provokes a drug intervention?
Screening for microalbuminuria in patients with type 1 diabetes is part of the diabetes annual review. It aims to detect the early stage of diabetic nephropathy before the onset of dipstick-positive proteinuria
(so-called macroalbuminuria). Diabetic nephropathy is a clinical syndrome of persistent proteinuria, hypertension and declining renal function. Patients with this complication have increased premature morbidity and mortality as a result of end-stage renal failure, cardiovascular disease and other diabetes complications, which cluster in this cohort. In well-controlled patients, the discovery of microalbuminuria after 15 years of diabetes would be typical of the natural history of this complication.
The issue surrounds the validity of this screening result. Urinary albumin excretion rates are highly variable, being affected by infection, posture and exercise, and this means that sampling procedures are very important. The test should be performed on a first-voided urine sample and, if positive, infection should be excluded by culture. If microalbuminuria is confirmed, then a timed overnight collection should be arranged for assessment of the albumin excretion rate; if this is also positive, a further two overnight collections should be organized. No treatment should be instituted on the basis of this one-off finding.
A2: If drug therapy were indicated, which would be the most appropriate choice of agent?
Evidence supports the use of ACE inhibitors to delay the progression of microalbuminuria towards diabetic nephropathy, even in the presence of normal blood pressure. A further consideration in this case, however, is that ACE inhibitors should not be used in pregnancy and so appropriate contraceptive measures should be instituted before prescription is considered.
A3: What sort of follow-up is indicated?
Once a definitive diagnosis has been made, annual screening is probably satisfactory. This is definitely the case if the repeat urine tests are negative. If a diagnosis of persistent microalbuminuria is made and the patient opted to take an ACE inhibitor, sequential urine testing is unlikely to alter management – hence, yearly screening as part of the annual review would be appropriate.
A4: What other issues need to be addressed with regard to cardiovascular risk?
This person has no evidence of coronary heart disease and she is currently normotensive, non-smoking and lean. In this age group there is no evidence to support the use of long-term lipid-lowering therapy or aspirin, and she has good glycaemic control. Apart from advice on keeping her weight under control and taking regular exercise, no other issues need to be addressed.
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OSCE counselling cases
OSCE COUNSELLING CASE 1.7 – ‘As someone with late-onset diabetes, should I be taking aspirin?’
‘Late-onset diabetes’ is an old term for non-insulin-dependent diabetes, now termed type 2 diabetes mellitus. The short answer to the question is ‘probably no’. This advice, however, is based more on consensus expert opinion than on trial evidence.
Patients with known coronary heart disease should receive secondary prevention with aspirin prescribed at a dose of 150 mg once daily. For patients with no evidence of coronary heart disease, primary prevention with aspirin 75 mg once daily used to be the norm but the risk of bleeding is now thought to outweigh the benefits. The outcome of a large trial (called ASCEND) assessing the use of aspirin in ‘low-risk’ type 2 diabetes is awaited.
OSCE COUNSELLING CASE 1.8 – ‘Why is my blood pressure so difficult to control?’
Hypertension is commonly associated with type 2 diabetes but is difficult to treat to target. This difficulty is made worse by the lowering of target levels, based on results of large clinical trials. In the UKPDS, blood pressure targets were less stringent than those that are now advocated for routine primary care (140/80 mmHg in type 2 diabetes); nevertheless, more than one-third of patients required three or more antihypertensive drugs. Added to this is the tendency for blood pressure to rise with age and obesity.
All of the major classes of antihypertensive agent can be used in patients with diabetes and raised blood pressure, and all classes produce an equivalent antihypertensive action and achieve target levels in a similar proportion of patients. Current guidelines support the use of ACE inhibitors as first-line in diabetes, followed by calcium channel blockers and low-dose diuretics.