20 Heart Protection Study Collaborative Group. MRC/BHF heart protection study of cholesterol lowering with simvastatin in 20 536 high-risk individuals: a randomised placebo-controlled trial
Correspondence to: Dr Miles Fisher, Wards 4 & 5, Glasgow Royal Infirmary, Glasgow, G4 0SF, UK; miles.fisher@northglasgow. scot.nhs.uk _________________________ T he excessive cardiovascular morbidity and mortality associated with diabetes (sometimes termed ‘‘the burden of heart disease in diabetes’’) has been recognised for a long time. Because of this, I have suggested that diabetes should be defined as a state of premature cardiovascular death which is associated with chronic hyperglycaemia and may also be associated with blindness and renal failure. This was first placed in context by the Framingham study, where middle aged people with diabetes had an increased coronary heart disease morbidity and mortality that could not be explained by the traditional cardiovascular risk factors of smoking, age, raised cholesterol, raised blood pressure, or obesity. This suggested a possible unique role for diabetes as a risk factor for the development of cardiovascular disease. Women with diabetes had the same prevalence of cardiovascular problems as men with diabetes, greatly increasing the risk compared to non-diabetic women, leading to the phrase ‘‘women with diabetes loose the protection of their gender’’. An excess of congestive cardiac failure was also noted that could not be explained by the presence of coronary heart disease, adding support to the existence of a possible ‘‘diabetic cardiomyopathy’’. From a critical perspective, however, this study was guilty of many of the problems that have affected research in this area ever since. A combination of patients with type 1 and type 2 diabetes was studied, and no attempt was made to classify the type of diabetes in an individual subject. The diagnostic criteria for diabetes were not consistent within the various publications from the Framingham study, leading to differing numbers of patients with diabetes in different publications. The number of subjects with diabetes was very small, which may have exaggerated the risks of some of the end points, such as cardiac failure in women with diabetes. The small number of subjects also means that the Framingham equation based on these data is much less exact for estimating cardiovascular risk in people with diabetes. Only middle aged and elderly subjects were studied, where the absolute risk is highest, and no attempt was made to study younger diabetic subjects, where the relative risk for people with diabetes is extraordinarily raised compared to non-diabetic subjects, yet the absolute risk remains relatively low. A recent review by Timmis described considerations in the cardiological treatment of people with diabetes. This review examines the possible differing mechanisms of heart disease in people with type 1 and type 2 diabetes. The effects of measures to control blood glucose on vascular outcomes are described in these groups of patients. Finally, studies on the reduction of cardiovascular risk in diabetes by the treatment of hypertension and dyslipidaemia, including several newer publications in this area, are described in detail.