Diabetes: managing dyslipidaemia


The term dyslipidaemia is used to describe a group of conditions in which there are abnormal levels of lipids and lipoproteins in the blood. Abnormalities of lipid metabolism are present in people with both type 1 and type 2 diabetes. The nature of these abnormalities is complex, but the core components of diabetic dyslipidaemia are elevated circulating levels of triglycerides and decreased circulating levels of high-density lipoprotein cholesterol (HDL-C). In addition, the number of small, dense lipoprotein particles is raised. Consequently — although the cholesterol content of these particles may be low — small, dense low-density lipoprotein cholesterol (LDL-C) is raised. Total cholesterol and LDL-C may be normal if glycaemic control is adequate.[1][2] Triglycerides and cholesterol are the main lipids of interest. The main classes of lipoprotein considered in this review are low-density lipoproteins (LDL) and high-density lipoproteins (HDL). Diagnosis: A diagnosis of diabetic dyslipidaemia requiring drug treatment is determined by the person's lipid profile and level of cardiovascular risk. The classification of cardiovascular risk and lipid targets for drug treatment differ between the USA[3] and the UK,[4]and the rest of Europe.[5] While it is accepted that people with diabetes are at high risk of CVD,[6][7] in the UK and USA this high-risk group is stratified further to target those most likely to benefit from treatment. However, the European guidelines on CVD prevention classify as all high risk people with type 2 diabetes, and with type 1 diabetes and microalbuminuria. Treatment targets for the UK and USA and the rest of Europe are shown in table 1. These targets apply to people with type 2 diabetes. It is acknowledged that in the USA,[8] there is a case for offering drug treatment at lower lipid levels in people at high cardiovascular risk. In the USA, an "optional" goal for LDL-C of 1.81 mmol/L (70 mg/dL) is considered in people with high cardiovascular risk;[8]and the Canadian Diabetic Association recommends a goal for LDL-C of 2.0 mmol/L or less in similarly high-risk people.[9] Although these targets apply to people with type 2 diabetes, in clinical practice they are often extrapolated to people with type 1 diabetes. Population: For this review, we have included studies of adults with type 1 and type 2 diabetes, including those with concurrent hypertension, and we have used UK (NICE) guidelines to determine level of risk. The UKPDS (United Kingdom Prospective Diabetes Study) tool, which includes data from people with diabetes, was used to calculate level of cardiovascular risk only.[10] Subpopulations are described in detail in the description of individual studies where appropriate. Studies in children were excluded. Studies of adults with diabetes and microalbuminuria or nephropathy are covered in a separate review (see review on diabetic nephropathy).