Atherosclerosis is the major cause of death in patients with diabetes. Low‐density lipoprotein (LDL) being the most important cholesterol‐carrying lipoprotein has been studied extensively in both diabetes and non‐diabetes. This paper reviews the literature but also focuses on the precursors of LDL and in particular the postprandial apo B‐containing lipoproteins. Abnormalities in the postprandial lipoproteins and alteration in chylomicron assembly and clearance are discussed and the evidence presented suggesting the importance of dysregulation of these lipoproteins in atherosclerotic progression. The relationship between chylomicron production in the intestine and hepatic release of very low‐density lipoproteins (VLDL) is explored, as is the interrelationship between clearance rates of these lipoproteins. The size of LDL influences its atherogenicity. VLDL composition and size in relation to its influence on LDL is discussed. The effect of diet on the composition of lipoproteins and the relationship between fatty acid composition and clearance is reviewed. Evidence that diabetic control beneficially alters lipoprotein composition is presented suggesting how improved diabetic control may reduce atherosclerosis. The review concludes with a discussion on the effect of the apo B‐containing lipoproteins and their modification through glycation and oxidation on macrophage and endothelial function. Copyright © 2001 John Wiley & Sons, Ltd.