Anticardiolipin and anti-beta 2 glycoprotein I antibodies are associated with an increased tendency to thrombosis by various mechanisms. This study aimed to evaluate the association between micro and macrovascular complications of diabetes and anticardiolipin and anti-beta 2 glycoprotein I antibodies. Forty-six patients with type 2 diabetes mellitus (T2DM) were studied. Twenty-one patients had coronary artery disease as a macrovascular complication. Twenty-five age and sex matched healthy subjects formed a control group. Anticardiolipin IgM, IgG, anti-beta 2 glycoprotein IgM and IgG antibody levels were studied in both patient and control groups. Diabetic patients with ischaemic heart disease had significantly higher titres of anticardiolipin IgG antibody than patients without ischaemic heart disease (P < 0.001). However, none of these patients had an anticardiolipin IgG antibody level higher than 20 GPL, which is accepted as a clinically significant value, so this association may not be clinically important. There was no association with the microvascular complications. There was also no significant association between anti-beta 2 glycoprotein I antibodies in type 2 diabetic patients and micro and macrovascular complications. Anticardiolipin and anti-beta 2 glycoprotein I antibodies do not have a major role in the pathogenesis of diabetic complications in type 2 diabetic patients. Prospective studies of large populations are needed to explore this association further. (c) 2004 Elsevier Ireland Ltd. All rights reserved.