Apolipoprotein (a) levels in type 1 and type 2 diabetes mellitus

Type 1 and type 2 diabetes mellitus are both characterized by increased cardiovascular mortality and morbidity. Since several reports have indicated that apolipoprotein (a) [apo(a)] levels are positively associated with an increased risk of macrovascular disease, we investigated whether apo(a) levels are elevated in both types of diabetes mellitus and may thus represent an independent risk factor for atherosclerotic disease. Apo(a) concentrations in type 1 diabetic patients were not significantly different from matched controls (276 +/- 78 vs 149 +/- 46 units/l). Type 2 diabetic patients had considerably higher levels of apo(a) than matched controls (471 +/- 89 vs 221 +/- 61 units/l, P = 0.06), though the difference was not statistically significant. However, concentrations of apo(a) were above 300 units/l in 36% of type 1 and 67% of type 2 diabetic patients, but in only 14% and 25% respectively of matched control subjects. Plasma triglycerides were positively and independently correlated with apo(a) levels in both diabetic and non-diabetic subjects. On the other hand, no significant correlation was found between apo(a) levels and glycosylated haemoglobin, total cholesterol or high density lipoprotein cholesterol in any of the groups studied. In conclusion, apo(a) levels are not significantly elevated either in type 1 or type 2 diabetic patients without proteinuria and in moderate metabolic control; however, levels above 300 units/l were 2.6 times more frequent in both types of diabetes mellitus than in carefully age-, sex-, and weight-matched control subjects.