Despite overwhelming evidence of the benefits of statins for people with diabetes, many eligible patients either are still not receiving them or are being prescribed an inappropriate statin (not potent enough) or too low a dose to achieve recommended cholesterol target levels. Hence they remain at high risk of cardiovascular disease. Increasingly, the decision to prescribe statins is being made by a patient’s GP. This article looks at the influences on GPs’ prescribing of statins, in terms of current evidence and national guidelines.

Between 3% and 3.5% of patients in each general practice in the UK have diabetes, mostly type 2 (Harvey et al, 2002). Cardiovascular disease (CVD) accounts for the greatest proportion of mortality and morbidity in these patients. Prevention of CVD is therefore of major importance in this patient group, and the management of raised cholesterol in people with diabetes is a key issue.

Increasingly, the management of people with diabetes is provided by the primary care in-house diabetes clinic, and the decision to prescribe statins is made by a patient’s GP. This article looks at the factors that are most likely to influence this decision, in terms of current evidence and national guidelines.

Particular reference will be made to data from the Heart Protection Study (HPS; Collins, 2003) and the more recently reported Collaborative Atorvastatin Diabetes Study (CARDS; Colhoun et al, 2004) and A raNdomised, Double blind, study to compare Rosuvastatin (10 mg and 20 mg) and atOrvastatin (10 Mg and 20 mg) in patiEnts with type 2 DiAbetes (ANDROMEDA; Betteridge and Gibson, 2004).

* HPS compared the use of 40 mg simvastatin vs placebo. It included the largest subsection of people with diabetes ever studied and produced highly significant data.

* CARDS specifically investigated people with diabetes and resulted in an impressive 37% reduction in primary cardiovascular endpoints.

* ANDROMEDA and CORALL (COmpare the effects of Rosuvastatin with Atorvastatin on apo B/apo A-1 ratio in patients with type 2 diabetes meLLitus and dyslipidaemia; Wolffenbuttel et al, 2005) are comparative studies of rosuvastatin and atorvastatin.

All these trials used optimum doses of powerful statins. The National Institute for Health and Clinical Excellence (NICE) statin guidelines are currently under evaluation, and their influence in terms of people with diabetes will also be considered.

Evidence for the benefits of statins in diabetes

A number of large clinical trials have established statins as effective agents in the prevention of both primary and secondary coronary heart disease (CHD; Downs et al, 1998; Shepherd et al, 2002; Collins et al, 2003; Sever et al, 2003), with a clear association between cholesterol reduction and outcome benefits (Figure 1; Gould et al, 1998). Many of these studies included significant sub-groups of people with diabetes.

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The HPS demonstrated uniform risk reduction across a wide range of patients, including those with diabetes (Collins et al, 2003). Indeed, type 2 diabetes was an independent predictor of benefit from statin therapy, with a 1 mmol/l reduction in low-density lipoprotein (LDL)-cholesterol resulting in a 22% reduction in risk of a first vascular event, independent of baseline LDL-cholesterol levels.

These data are consistent with a recent meta-analysis of diabetes sub-groups from statins trials, which demonstrated that cholesterol reduction may reduce the risk of primary and secondary cardiovascular events by 22% and 24% respectively (Vijan and Hayward, 2004).

Relative risk reduction is similar in primary and secondary prevention trials; however, as patients with established CHD are at greater absolute risk, statin therapy achieves substantially higher absolute reduction in secondary prevention trials than in primary prevention studies (Vijan and Hayward, 2004). Similarly, patients with type 2 diabetes are at higher absolute risk than those without diabetes, therefore statin therapy results in greater absolute benefit in patients with type 2 diabetes (Vijan and Hayward, 2004).

Data from studies such as the HPS therefore suggest that all patients with type 2 diabetes should qualify for statin therapy. CARDS further illustrated the benefits of cholesterol reduction in patients with type 2 diabetes (Colhoun et al, 2004). In this study of more than 2800 people with type 2 diabetes and at least one other CHD risk factor, an LDL-cholesterol reduction of 40% and triglyceride reduction of 19% were associated with a 37% reduction in major coronary events and a 48% reduction in stroke.

A meta-analysis of lipid-lowering trials in type 2 diabetes has concluded that the number needed to treat to prevent one CHD event was 13.8/4.9 years of secondary prevention and 34.5/4.3 years for primary prevention (Vijan and Hayward, 2004). Thus, compared with commonly adopted medical interventions, cholesterol reduction appears to be cost-effective even in the absence of overt CVD.