Can measurement of serum lipoprotein [a] and apolipoprotein-B be of prognostic value in patients with type 2 diabetes mellitus with myocardial infarction and peripheral vascular disease?

Current clinical guidelines require that five indices [total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and the total/HDL cholesterol ratio] be measured or calculated to assess the lipid-related risk of vascular disease. Recently, quantification of plasma Lp[a] and Apo-B was proposed as recent clinical markers that will allow better prediction of coronary and peripheral arterial disease. This study prospectively examined whether high levels of Lp[a] and Apo-B have a significant risk and prognostic value in type 2 diabetic patients with myocardial infarction and peripheral vascular disease. The patients included in the study were selected properly from outpatient clinics of Vascular Surgery Unit as well as Internal Medicine Department [Cardiovascular Unit], Mansoura University. The patients were divided into 4 groups: Group I [n=15]: Type 2 DM with no CAD and no PVD. Group II [n=15]: Type 2 DM with history of myocardial infarction and No PVD. Group Ill [n=15]: Type 2 DM with no history of myocardial infarction but have symptomatic PVD. Group IV [n=15]: Type 2 DM with history of myocardial infarction and have PVD. Patients with acute illness or taking Niacin, Estrogen replacement or antibiotics were excluded. All patients were subjected to thorough history taking, cardiovascular and peripheral vascular system evaluation including BMI, ABI, ECG, Doppler US echocardiogram as well as peripheral vascular angiography. Laboratory evaluation of our patients included assessment of diabetic state, HbA1c, standard lipid profile parameters as well as evaluation of Lp[a] and Apo-B. Serum level of Lp[a] and Apo-B showed highly statistically significant results when comparing group I with any group of type 2 diabetic patients complicated with either MI or PVD [P<0.001]. However, serum apo-B level was highly significant in those complicated with PVD [P<0.001], while serum Lp[a] was statistically higher in those having myocardial infarction [P=0.03]. Our study revealed that elevation of serum level of both Lp[a] and Apo-B were significantly correlated with occurrence of myocardial infarction and different grades of peripheral vascular insufficiency in type 2 diabetic individuals. However, increased serum level of Lp[a] showed higher significant prediction for occurrence of MI while, elevation of serum level of Apo-B predict more the occurrence of PVD among our patients. Evaluation of serum Lp[a] and Apo-B levels should be considered a new risk factor and is of prognostic value for occurrence of vascular complications in type 2 diabetic patients. More population-based prospective studies are needed to answer the question definitively of whether Lp[a] and Apo-B levels are more predictive of CAD and PVD in type 2 diabetic individuals than the traditional lipid parameters