LIPOPROTEIN (A) AND DIABETES-MELLITUS

Lp(a) has atherogenic and thrombotic properties and is considered to b e a major risk factor for the development of atherosclerotic disease. The risk of cardiovascular disease is increased in both insulin-depend ent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), and Lp (a) has attracted attention as a potential risk factor in diabetic pat ients. Lp(a) levels are ''probably'' elevated in IDDM patients and rel ated to altered metabolic control and increased urinary albumin excret ion rate or renal insufficiency, although results are controversial. T here appears to be a real difference between the Lp(a) of patients wit h proliferative diabetic retinopathy and those with or without backgro und retinopathy. The plasma Lp(a) level may therefore be associated wi th microangiopathy in some IDDM patients. However, data relating Lp(a) to complications of diabetes are limited, a nd the literature is conf licting. The few available data suggest that Lp(a) is not elevated in NIDDM patients and that there is no strong link between blood glucose control and plasma Lp(a). There is no clear evidence asto whether Lp(a ) is related to microalbuminuria in NIDDM patients. There is little ev idence for a correlation between increased risk of cardiovascular dise ase and plasma Lp(a) among diabetic patients. However, some diabetic p atients with coronary heart disease have elevated plasma Lp(a), which seems to be correlated with genetic factors (especially the isoforms o f apolipoprotein a) rather than to diabetes per se. Lp(a) synthesis an d catabolism could be influenced by insulin or by diabetes and its met abolic concomitants. The atherogenic and thrombogenic potential of Lp( a) could also be increased in diabetic patients. Plasma Lp(a) should b e measured for both IDDM and NIDDM patients. If the Lp(a) level is ele vated, it seems reasonable to check the other major vascular risk fact ors.